OXYACETYLENE
WELDING

AND CUTTING

ELECTRIC AND
THERMIT WELDING

TvlANUY

Oxy-Acetylene
Welding and Cutting

Electric, Forge and Thermit
Welding

Together with Related Methods and
Materials Used in Metal Working

And

The Oxygen Process for
Removal of Carbon

By

HAROLD P. MANLY

Chief Engineer The American Bureau
of Engineering

CHICAGO

FREDERICK J . DRAKE & CO.
Publishers

Copyright 1916

By Frederick J. Drake & Co.

Chicago

PREFACE

In the preparation of this work, the object has been
to cover not only the several processes of welding, but
also those other processes which are so closely allied
in method and results as to make them, a part of the
whole subject of joining metal to metal with the aid
of heat.

The workman who wishes to handle his trade from
start to finish finds that it is necessary to become
familiar with certain other operations which precede
or follow the actual joining of the metal parts, the
purpose of these operations being to add or retain
certain desirable qualities in the materials being han-
dled. For this reason the following subjects have
been included : Annealing, tempering, hardening, heat
treatment and the restoration of steel.

In order that the user may understand the under-
lying principles and the materials employed in this
work, much practical information is given on the
uses and characteristics of the various metals ; on the
production, handling and use of the gases and other
materials which are a part of the equipment ; and on
the tools and accessories for the production and han-
dling of these materials.

An examination will show that the greatest useful-
ness of this book lies in the fact that all necessary
information and data has been included in one vol-
ume, making it possible for the workman to use one
source for securing a knowledge of both principle

343651

6 < PREFACE

and practice, preparation and finishing of the work,
and both large and small repair work as well as manu-
facturing methods used in metal working.

An effort has been made to eliminate all matter
which is not of direct usefulness in practical work,
while including all" that those engaged in this trade
find necessary. To this end, the descriptions have
been limited to those methods and accessories which
are found in actual use today. For the. same reason,
the work includes the application of the rules laid
down by the insurance underwriters which govern
this work as well as instructions for the proper care
and handling of the generators, torches and materials
found in the shop.

Special attention has been given to definite direc-
tions for handling the different metals and alloys
which must be handled. The instructions have been
arranged to form rules which are placed in the order
of their use during the work described and the work
has been subdivided in such a wray that it will be
found possible to secure information on any one point
desired without the necessity of spending time in
other fields.

The facts which the expert welder and metal-
worker finds it most necessary to have readily avail-
able have been secured and prepared especially for
this work, and those of most general use have been
combined with the chapter on welding practice to
which they apply.

The size of this volume has been kept as small as
possible, but an examination of the alphabetical index
will show that the range of subjects and details cov-
ered is complete in all respects. This has been accom-
plished through careful classification of the contents

•PREFACE 7

and the elimination of all repetition and all theoret-
ical, historical and similar matter that is not abso-
lutely necessary.

Free use has been made of the information given
by those manufacturers who are recognized as the
leaders in their respective fields, thus insuring that
the work is thoroughly practical and that it repre-
sents present day methods and practice.

THE AUTHOR.

CONTENTS

CHAPTER I

PAGE

METALS AND ALLOYS — HEAT TREATMENT: — The Use and
Characteristics of the Industrial Alloys and Metal Ele-
ments— Annealing, Hardening, Tempering and Case Hard-
ening of Steel 11

CHAPTER II

WELDING MATERIALS : — Production, Handling and Use of the
Gases, Oxygen and Acetylene — Welding Eods — Fluxes —
Supplies and Fixtures 33

CHAPTER III

ACETYLENE GENERATORS: — Generator Requirements and
Types — Construction — Care and Operation of Generators. 60

CHAPTER IV

WELDING INSTRUMENTS: — Tank and Regulating Valves and
Gauges — High, Low and Medium Pressure Torches — Cut-
ting Torches — Acetylene-Air Torches 85

CHAPTER V

OXY-ACETYLENE WELDING PRACTICE: — Preparation of Work
— Torch Practice — Control of the Flame — Welding Vari-
ous Metals and Alloys — Tables of Information Required
in Welding Operations 106

CHAPTER VI

ELECTRIC WELDING: — Resistance Method — Butt, Spot and
Lap Welding — Troubles and Remedies — Electric Arc

Welding 142

9

10 CONTENTS

CHAPTER VII

PAGE

HAND FORGING AND WELDING: — Blacksmithing, Forging
and Bending — Forge Welding Methods 170

CHAPTER VIII

SOLDERING, BRAZING AND THERMIT WELDING: — Soldering
Materials and Practice — Brazing — Thermit Welding. .. .188

CHAPTER IX
OXYGEN PROCESS FOR EEMOVAL OF CARBON 207

INDEX 211

OXY-ACETYLENE WELDING AND

CUTTING, ELECTRIC AND

THERMIT WELDING

CHAPTER I

METALS AND THEIR ALLOYS— HEAT TREATMENT
THE METALS

Iron. — Iron, in its pure state, is a soft, white, easily
worked metal. It is the most important of all the
metallic elements, and is, next to aluminum, the com-
monest metal found in the earth.

Mechanically speaking, we have three kinds of iron :
wrought iron, cast iron and steel. Wrought iron is
very nearly pure iron; cast iron contains carbon and
silicon, also chemical impurities; and steel contains a
definite proportion of carbon, but in smaller quanti-
ties than cast iron.

Pure iron is never obtained commercially, the metal
always being mixed with various proportions of car-
bon, silicon, sulphur, phosphorus, and other elements,
making it more or less suitable for different purposes.
Iron is magnetic to the extent that it is attracted by
magnets, but it does not retain magnetism itself, as
does steel. Iron forms, with other elements, many
important combinations, such as its alloys, oxides,
and sulphates.

11

12 V/ELDING

Cast Iron. — Metallic iron is separated from iron
ore in the blast furnace (Figure 1), and when allowed
to run into moulds is called cast iron. This form is
used for engine cylinders and pistons, for brackets,
covers, housings and at any point where its brittle-

Figure 1. — Section Through a Blast Furnace

ness is not objectionable. Good cast iron breaks with
a gray fracture, is free from blowholes or roughness,
and is easily machined, drilled, etc. Cast iron is
slightly lighter than steel, melts at about 2,400 de-
grees in practice, is about one-eighth as good an elec-
trical conductor as copper and has a tensile strength
of 13,000 to 30,000 pounds per square inch. Its com-

METALS AND THEIR ALLOYS— HEAT TREATMENT 13

pressive strength, or resistance to crushing, is very
great. It has excellent wearing qualities and is not
easily warped and deformed by heat. Chilled iron
is cast into a metal mould so that the outside is cooled
quickly, making the surface very hard and difficult
to cut and giving great resistance to wear. It is used
for making cheap gear wheels and parts that must
withstand surface friction.

Malleable Cast Iron. — This is often called simply
malleable iron. It is a form of cast iron obtained by
removing much of the carbon from cast iron, making
it softer and less brittle. It has a tensile strength of
25,000 to 45,000 pounds per square inch, is easily
machined, will stand a small amount of bending at a
low red heat and is used chiefly in making brackets,
fittings and supports where low cost is of considerable
importance. It is often used in cheap constructions
in place of steel forgings. The greatest strength of a
malleable casting, like a steel forging, is in the sur-
face, therefore but little machining should be done.

Wrought Iron. — This grade is made by treating the
cast iron to remove almost all of the carbon, silicon,
phosphorus, sulphur, manganese and other impuri-
ties. This process leaves a small amount of the slag
from the ore mixed with the wrought iron.

Wrought iron is used for making bars to be ma-
chined into various parts. If drawn through the rolls
at the mill once, while being made, it is called "muck
bar;" if rolled twice, it is called "merchant bar"
(the commonest kind), and a still better grade is made
by rolling a third time. Wrought iron is being grad-
ually replaced in use by mild rolled steels.

Wrought iron is slightly heavier than cast iron, is
a much better electrical conductor than either cast

14 WELDING

iron or steel, has a tensile strength of 40,000 to 60,000
pounds per square inch and costs slightly more than
steel. Unlike either steel or cast iron, wrought iron
does not harden when cooled suddenly from a red heat.

Grades of Irons. — The mechanical properties of cast
iron differ greatly according to the amount of other
materials it contains. The most important of these
contained elements is carbon, which is present to a
degree varying from 2 to 5% per cent. When iron
containing much carbon is quickly cooled and then
broken, the fracture is nearly white in color and the
metal is found to be hard and brittle. When the iron
is slowly cooled and then broken the fracture is gray
and the iron is more malleable and less brittle. If
cast iron contains sulphur or phosphorus, it will show
a white fracture regardless of the rapidity of cooling,
being brittle and less desirable for general work.

Steel. — Steel is composed of extremely minute par-
ticles of iron and carbon, forming a network of layers
and bands. This carbon is a smaller proportion of the
metal than found in cast iron, the percentage being
from T3Q- to 2!/2 per cent.

Carbon steel is specified according to the number of
"points" of carbon, a point being one one-hundredth
of one per cent of the weight of the steel. Steel may
contain anywhere from 30 to 250 points, which is
equivalent to saying, anywhere from -f$ to 2^ per
cent, as above. A 70-point steel would contain 70/100
of one per cent or TT0- of one per cent of carbon by
weight. The percentage of carbon determines the
hardness of the steel, also many other qualities, and
its suitability for various kinds of work. The more
carbon contained in the steel, the harder the metal
will be, and, of course, its brittleness increases with

METALS AND THEIR ALLOYS— HEAT TREATMENT 15

the hardness. The smaller the grains or particles of
iron which are separated by the carbon, the stronger
the steel will be, and the control of the size of these
particles is the object of the science of heat treatment.

In addition to the carbon, steel may contain the
following :
Silicon, which increases the hardness, brittleness,

strength and difficulty of working if from 2 to 3

per cent is present.
Phosphorus, which hardens and weakens the metal

but makes it easier to cast. Three-tenths per cent

of phosphorus serves as a hardening agent and may

be present in good steel if the percentage of carbon

is low. More than this weakens the metal.
Sulphur, which tends to make the metal hard and

filled with small holes.
Manganese, which makes the steel so hard and tough

that it can with difficulty be cut with steel tools.

Its hardness is not lessened by annealing, and it has

great tensile strength.

Alloy steel has a varying but small percentage of
other elements mixed with it to give certain desired
qualities. Silicon steel and manganese steel are some-
times classed as alloy steels. This subject is taken up
in the latter part of this chapter under Alloys, where
the various combinations and their characteristics are
given consideration.

Steel has a tensile strength varying from 50,000 to
300,000 pounds per square inch, depending on the
carbon percentage and the other alloys present, as
well as upon the texture of the grain. Steel is heavier
than cast iron and weighs about the same as wrought
iron. It is about one-ninth as good a conductor of
electricity as copper.

16

WELDING

Steel is made from cast iron by three principal
processes: the crucible, Bessemer and open hearth.

Crucible steel is made by placing pieces of iron in
a clay or graphite crucible, mixed with charcoal and a
small amount of any desired alloy. The crucible is
then heated with coal, oil or gas fires until the iron
melts, and, by absorbing the desired elements and giv-
ing up or changing its percentage of carbon, becomes

Figure 2. — A Bessemer Converter

steel. The molten steel is then poured from the cru-
cible into moulds or bars for use. Crucible steel may
also be made by placing crude steel in the crucibles in
place of the iron. This last method gives the finest
grade of metal and the crucible process in general
gives the best grades of steel for mechanical use.

Bessemer steel is made by heating iron until all the
undesirable elements are burned out by air blasts
which furnish the necessary oxygen. The iron is
placed in a large retort called a converter (Figure
2), being poured, while at a melting heat, directly

METALS AND THEIR ALLOYS— HEAT TREATMENT 17

from the blast furnace into the converter. While the
iron in the converter is molten, blasts of air are forced
through the liquid, making it still hotter and burning
out the impurities together with the carbon and man-
ganese. These two elements are then restored to the
iron by adding spiegeleisen (an alloy of iron, carbon
and manganese) . A converter holds from 5 to 25 tons
of metal and requires about 20 minutes to finish a
charge. This makes the cheapest steel.

Figure 3. — An Open Hearth Furnace

Open hearth steel is made by placing the molten
iron in a receptacle while currents of air pass over it,
this air having itself been highly heated by just pass-
ing over white hot brick (Figure. 3). Open hearth
steel is considered more uniform and reliable than
Bessemer, and is used for springs, bar steel, tool steel,
steel plates, etc.

Aluminum is one of the commonest industrial
metals. It is used for gear cases, engine crank cases,
covers, fittings, and wherever lightness and moderate
strength are desirable.

Aluminum is about one-third the weight of iron

18 WELDING

and about the same weight as glass and porcelain ; it
is a good electrical conductor (about one-half as good
as copper) ; is fairly strong itself and gives great
strength to other metals when alloyed with them. One
of the greatest advantages of aluminum is that it will
not rust or corrode under ordinary conditions. The
granular formation of aluminum makes its strength
very unreliable and it is too soft to resist wear.

Copper is one of the most important metals used in
the trades, and the best commercial conductor of elec-
tricity, being exceeded in this respect only by silver,
which is but slightly better. Copper is very malleable
and ductile when cold, and in this state may be easily
worked under the hammer. Working in this way
makes the copper stronger and harder, but less duc-
tile. Copper is not affected by air, but acids cause
the formation of a green deposit called verdigris.

Copper is one of the best conductors of heat, as
well as electricity, being used for kettles, boilers, stills
and wherever this quality is desirable. Copper is also
used in alloys with other metals, forming an impor-
tant part of brass, bronze, german silver, bell metal
and gun metal. It is about one-eighth heavier than
steel and has a tensile strength of about 25,000 to
50,000 pounds per square inch.

Lead. — The peculiar properties of lead, and espe-
cially its quality of showing but little action or chem-
ical change in the presence of other elements, makes
it valuable under certain conditions of use. Its prin-
cipal use is in pipes for water and gas, coverings for
roofs and linings for vats and tanks. It is also used
to coat sheet iron for similar uses and as an important
part of ordinary solder.

Lead is the softest and weakest of all the commer-

METALS AND THEIR ALLOYS— HEAT TREATMENT 19

cial metals, being very pliable and inelastic. It should
be remembered that lead and all its compounds are
poisonous when received into the system. Lead is
more than one-third heavier than steel, has a tensile
strength of only about 2,000 pounds per square inch,
and is only about one-tenth as good a conductor of
electricity as copper.

Zinc. — This is a bluish-white metal of crystalline
form. It is brittle at ordinary temperatures and be-
comes malleable at about 250 to 300 degrees Fahren-
heit, but beyond this point becomes even more brittle
than at ordinary temperatures. Zinc is practically
unaffected by air or moisture through becoming cov-
ered with one of its own compounds which immedi-
ately resists further action. Zinc melts at low tem-
peratures, and when heated beyond the melting point
gives off very poisonous fumes.

The principal use of zinc is as an alloy with other
metals to form brass, bronze, german silver and bear-
ing metals. It is also used to cover the surface of
steel and iron plates, the plates being then called
galvanized.

Zinc weighs slightly less than steel, has a tensile
strength of 5,000 pounds per square inch, and is not
quite half as good as copper in conducting electricity.

Tin resembles silver in color and luster. Tin is
ductile and malleable and slightly crystalline in form,
almost as heavy as steel, and has a tensile strength of
4,500 pounds per square inch.

The principal use of tin is for protective platings
on household utensils and in wrappings of tin-foil.
Tin forms an important part of many alloys such as
babbitt, Britannia metal, bronze, gun metal and bear-
ing metals.

20 WELDING

Nickel is important in mechanics because of its
combinations with other metals as alloys. Pure nickel
is grayish-white, malleable, ductile and tenacious. It
weighs almost as much as steel and, next to man-
ganese, is the hardest of metals. Nickel is one of the
three magnetic metals, the others being iron and co-
balt. The commonest alloy containing nickel is ger-
man silver, although one of its most important alloys
is found in nickel steel. Nickel is about ten per cent
heavier -than steel, and has a tensile strength of 90,000
pounds per square inch.

Platinum. — This metal is valuable for two reasons:
it is not affected by the air or moisture or any ordi-
nary acid or salt, and in addition to this property it
melts only at the highest temperatures. It is a fairly
good electrical conductor, being better than iron or
steel. It is nearly three times as heavy as steel and
its tensile strength is 25,000 pounds per square inch.

ALLOYS

An alloy is formed by the union of a metal with
some other material, either metal or non-metallic,
this union being composed of two or more elements
and usually brought about by heating the substances
together until they melt and unite. Metals are al-
loyed with materials which have been found to give
to the metal certain characteristics which are desired
according to the use the metal will be put to.

The alloys of metals are, almost without exception,
more important from an industrial standpoint than
the metals themselves. There are innumerable pos-
sible combinations, the most useful of which are here
classed under the head of the principal metal entering
into their composition.

METALS AND THEIR ALLOYS— HEAT TREATMENT 21

Steel. — Steel may be alloyed with almost any of the
metals or elements, the combinations that have proven
valuable numbering more than a score. The principal
ones are given in alphabetical order, as follows :

Aluminum is added to steel in very small amounts
for the purpose of preventing blow holes in castings.

Boron increases the density and toughness of the
metal.

Bronze, added by alloying copper, tin and iron, is
used for gun metal.

Carbon has already been considered under the head
of steel in the section devoted to the metals. Carbon,
while increasing the strength and hardness, decreases
the ease of forging and bending and decreases the
magnetism and electrical conductivity. High carbon
steel can be welded only with difficulty. When the
percentage of carbon is low, the steel is called "low
carbon" or "mild" steel. This is used for rods and
shafts, and called " machine " steel. When the car-
bon percentage is high, the steel is called "high
carbon" steel, and it is used in the shop as tool steel.
One-tenth per cent of carbon gives steel a tensile
strength of 50,000 to 65,000 pounds per square inch ;
two-tenths per cent gives from 60,000 to 80,000 ; four-
tenths per cent gives 70,000 to 100,000, and six-tenths
per cent gives 90,000 to 120,000.

Chromium forms chrome steel, and with the further
addition of nickel is called chrome nickel steel. This
increases the hardness to a high degree and adds
strength without much decrease in ductility. Chrome
steels are used for high-speed cutting tools, armor
plate, files, springs, safes, dies, etc.

Manganese has been mentioned under Steel. Its
alloy is much used for high-speed cutting tools, the

22 WELDING

steel hardening when cooled in the air and being
called self-hardening.

Molybdenum is used to increase the hardness to a
high degree and makes the steel suitable for high-
speed cutting and gives it self-hardening properties.

Nickel, with which is often combined chromium,
increases the strength, springiness and toughness and
helps to prevent corrosion.

Silicon has already been described. It suits the
metal for use in high-speed tools.

Silver added to steel has many of the properties
of nickel.

Tungsten increases the hardness without making
the steel brittle. This makes the steel well suited for
gas engine valves as it resists corrosion and pitting.
Chromium and manganese are often used in com-
bination with tungsten when high-speed cutting tools
are made.

Vanadium as an alloy increases the elastic limit,
making the steel stronger, tougher and harder. It
also makes the steel able to stand much bending and
vibration.

Copper. — The principal copper alloys include brass,
bronze, german silver and gun metal.

Brass is composed of approximately one-third zinc
and two-thirds copper. It is used for bearings and
bushings where the speeds are slow and the loads
rather heavy for the bearing size. It also finds use
in washers, collars and forms of brackets where the
metal should be non-magnetic, also for many highly
finished parts.

Brass is about one-third as good an electrical con-
ductor as copper, is slightly heavier than steel and

METALS AND THEIR ALLOYS— HEAT TREATMENT 23

has a tensile strength of 15,000 pounds when cast
and about 75,000 to 100,000 pounds when drawn into
wire.

Bronze is composed of copper and tin in various
proportions, according to the use to which it is to
be put. There will always be from six-tenths to nine-
tenths of copper in the mixture. Bronze is used for
bearings, bushings, thrust washers, brackets and gear
wheels. It is heavier than steel, about 1/15 as good
an electrical conductor as pure copper and has a
tensile strength of 30,000 to 60,000 pounds.

Aluminum bronze, composed of copper, zinc and
• aluminum has high tensile strength combined with
ductility and is used for parts requiring this com-
bination.

Bearing bronze is a variable material, its composi-
tion and proportion depending on the maker and the
use for which it is designed. It usually contains
from 75 to 85 per cent of copper combined with
one or more elements, such as tin, zinc, antimony and
lead.

White metal is one form of bearing bronze con-
taining over 80 per cent of zinc together with cop-
per, tin, antimony and lead. Another form is made
with nearly 90 per cent of tin combined with copper
and antimony.

Gun metal bronze is made from 90 per cent copper
with 10 per cent of tin and is used for heavy bear-
ings, brackets and highly finished parts.

Phosphor bronze is used for very strong castings
and bearings. It is similar to gun metal bronze,
except that about l1/^ per cent of phosphorus has
been added.

Manganese bronze contains about 1 per cent of

24 WELDING

manganese and is used for parts requiring great
strength while being free from corrosion.

German silver is made from 60 per cent of copper
with 20 per cent each of zinc and nickel. Its high
electrical resistance makes it valuable for regulating
devices and rheostats.

Tin is the principal part of babbitt and solder. A
commonly used babbitt is composed of 89 per cent tin,
8 per cent antimony and 3 per cent of copper. A
grade suitable for repairing is made from 80 per
cent of lead and 20 per cent antimony. This last
formula should not be used for particular work or
heavy loads, being more suitable for spacers. In-
numerable proportions of metals are marketed under
the name of babbitt.

Solder is made from 50 per cent tin and 50 per cent
lead, this grade being called "half-and-half." Hard
solder is made from two-thirds tin and one-third
lead.

Aluminum forms many different alloys, giving in-
creased strength to whatever metal it unites with.

Aluminum brass is composed of approximately 65
per cent copper, 30 per cent zinc and 5 per cent alu-
minum. It forms a metal with high tensile strength
while being ductile and malleable.

Aluminum zinc is suitable for castings which must
be stiff and hard.

Nickel aluminum has a tensile strength of 40,000
pounds per square inch.

Magnalium is a silver-white alloy of aluminum
with from 5 to 20 per cent of magnesium, forming
a 'metal even lighter than aluminum and strong
enough to be used in making high-speed gasoline
engines.

METALS AND THEIR ALLOYS— HEAT TREATMENT 25
HEAT TREATMENT OF STEEL

The processes of heat treatment are designed to
suit the steel for various purposes by changing the
size of the grain in the metal, therefore the strength ;
and by altering the chemical composition of the al-
loys in the metal to give it different physical prop-
erties. Heat treatment, as applied in ordinary shop
work, includes the three processes of annealing, hard-
ening and tempering, each designed to accomplish a
certain definite result.

All of these processes require that the metal treated
be gradually brought to a certain predetermined
degree of heat which shall be uniform throughout the
piece being handled and, from this point, cooled ac-
cording to certain rules, the selection of wrhich forms
the difference in the three methods.

Annealing. — This is the process which relieves all
internal strains and distortion in the metal and
softens it so that it may more easily be cut, machined
or bent to the required form. In some cases anneal-
ing is used only to relieve the strains, this being the
case after forging or welding operations have been
performed. In other cases it is only desired to soften
the metal sufficiently that it may be handled easily.
In some cases both of these things must be accom-
plished, as after a piece has been forged and must
be machined. No matter what the object, the pro-
cedure is the same.

The steel to be annealed must first be heated to a
dull red. This heating should be done slowly so
that all parts of the piece have time to reach the same
temperature at very nearly the same time. The piece
may be heated in the forge, but a much better way is

26 WELDING

to heat in an oven or furnace of some type where
the work is protected against air currents, either hot
or cold, and is also protected against the direct action
of the fire.

Probably the simplest of all ovens for small tools is
made by placing a piece of ordinary gas pipe in the
fire (Figure 4), and heating until the inside of the
pipe is bright red. Parts placed in this pipe, after
one end has been closed, may be brought to the de-

Figure 4. — A Gaspipe Annealing Oven

sired heat without danger of cooling draughts or
chemical change from the action of the fire. More
elaborate ovens may be bought which use gas, fuel
oils or coal to produce the heat and in which the
work may be placed on trays so that the fire will not
strike directly on the steel being treated.

If the work is not very important, it may be with-
drawn from the fire or oven^, after heating to the
desired point, and allowed to cool in the air until all
traces of red have disappeared when held in a dark
place. The work should be held where it is reason-
ably free from cold air currents. If, upon touching
a pine stick to the piece being annealed, the wood

METALS AND THEIR ALLOYS— HEAT TREATMENT 27

does not smoke, the work may then be cooled in
water.

Better annealing is secured and harder metal may
be annealed if the cooling is extended over a number
of hours by placing the work in a bed of non-heat-
conducting material, such as ashes, charred bone,
asbestos fibre, lime, sand or fire clay. It should be
well covered with the heat retaining material and
allowed to remain until cool. Cooling may be accom-
plished by allowing the fire in an oven or furnace
to die down and go out, leaving the work inside the
oven with all openings closed. The greater the time
taken for gradual cooling from the red heat, the
more perfect will be the results of the annealing.

While steel is annealed by slow cooling, copper or
brass is annealed by bringing to a low red heat and
quickly plunging into cold water.

Hardening. — Steel is hardened by bringing to a
proper temperature, slowly and evenly as for an-
nealing, and then cooling more or less quickly, ac-
cording to the grade of steel being handled. The
degree of hardening is determined by the kind of
steel, the temperature from which the metal is cooled
and the temperature and nature of the bath into
which it is plunged for cooling.

Steel to be hardened is often heated in the fire
until at some heat around 600 to 700 degrees is
reached, then placed in a heating bath of molten lead,
heated mercury, fused cyanate of potassium, etc., the
heating bath itself being kept at the proper tempera-
ture by fires acting on it. While these baths have
the advantage of heating the metal evenly and to
exactly the temperature desired throughout without
any part becoming over or under heated, their dis-

28 WELDING

advantages consist of the fact that their materials
and the fumes are poisonous in most all cases, and if
not poisonous, are extremely disagreeable.

The degree of heat that a piece of steel must be
brought to in order that it may be hardened depends
on the percentage of carbon in the steel. The greater
the percentage of carbon, the lower the heat neces-
sary to harden.

To find the proper heat from which any steel must
be cooled, a simple test may be carried out provided

Figure 5. — Cooling the Test Bar for Hardening

a sample of the steel, about six inches long can be
secured. One end of this test bar should be heated
almost to its melting point, and held at this heat
until the other end just turns red. Now cool the
piece in water by plunging it so that both ends
enter at the same time (Figure 5), that is, hold it
parallel with the surface of the water when plunged
in. This serves the purpose of cooling each point
along the bar from a different heat. When it has
cooled in the water remove the piece and break it at
short intervals, about y2 inch, along its length. The
point along the test bar which was cooled from the

METALS AND THEIR ALLOYS— HEAT TREATMENT 29

best possible temperature will show a very fine
smooth grain and the piece cannot be cut by a file
at this point. It will be necessary to remember the
exact color of that point when taken from the fire,
making another test if necessary, and heat all pieces
of this same steel to this heat. It will be necessary
to have the cooling bath always at the same tempera-
ture, or the results cannot be alike.

While steel to be hardened is usually cooled in
water, many other liquids may be used. If cooled
in strong brine, the heat will be extracted much
quicker, and the degree of hardness will be greater.
A still greater degree of hardness is secured by cool-
ing in a bath of mercury. Care should be used with
the mercury bath, as the fumes that arise are poi-
sonous.

Should toughness be desired, without extreme hard-
ness, the steel may be cooled in a bath of lard oil,
neatsfoot oil or fish oil. To secure a result between
water and oil, it is customary to place a thick layer
of oil on top of water. In cooling, the piece will pass
thrugh the oil first, thus avoiding the sudden shock
of the cold water, yet producing a degree of hard-
ness almost as great as if the oil were not used.

It will, of course, be necessary to make a separate
test for each cooling medium used. If the fracture of
the test piece shows a coarse grain, the steel was too
hot at that point; if the fracture can be cut with a
file, the metal was not hot enough at that point.

When hardening carbon tool steel its heat should
be brought to a cherry red, the exact degree of heat
depending on the amount of carbon and the test made,
then plunged into water and held there until all
hissing sound and vibration ceases. Brine may be

30 WELDING

used for this purpose; it is even better than plain
water. As soon as the hissing stops, remove the
work from the water or brine and plunge in oil
for complete cooling.

In hardening high-speed tool steel, or air hardening
steels, the tool should be handled as for carbon steel,
except that after the body reaches a cherry red, the
cutting point must be quickly brought to a white heat,

Figure 6. — Cooling the Tool for Tempering

almost melting, so that it seems ready for welding.
Then cool in an oil bath or in a current of cool air.

Hardening of copper, brass and bronze is accom-
plished by hammering or working them while cold.

Tempering is the process of making steel tough
after it has been hardened, so that it will hold a
cutting edge and resist cracking. Tempering makes
the grain finer and the metal stronger. It does not
affect the hardness, but increases the elastic limit
and reduces the brittleness of the steel. In that tem-
pering is usually performed immediately after har-

METALS AND THEIR ALLOYS— HEAT TREATMENT 31

dening, it might be considered as a continuation of
the former process.

The work or tool to be tempered is slowly heated to
a cherry red and the cutting end is then dipped into
water to a depth of y% to % inch above the point
(Figure 6). As soon as the point cools, still leaving
the tool red above the part in water, remove the
work from the bath and quickly rub the end with a
fine emery cloth.

As the heat from the uncooled part gradually heats
the point again, the color of the polished portion
changes rapidly. When a certain color is reached,
the tool should be completely immersed in the water
until cold.

For lathe, planer, shaper and slotter tools, this
color should be a light straw.

Reamers and taps should be cooled from an ordi-
nary straw color.

Drills, punches and wood working tools should
have a brown color.

Blue or light purple is right for cold chisels and
screwdrivers.

Dark blue should be reached for springs and wood
saws.

Darker colors than this, ranging through green and
gray, denote that the piece has reached its ordinary
temper, that is, it is partially annealed.

After properly hardening a spring by dipping in
lard or fish oil. it should be held over a fire while
still wet with the oil. The oil takes fire and burns
off, properly tempering the spring.

Remember that self -hardening steels must never be
dipped in water, and always remember for all work

32 WELDING

requiring degrees of heat, that the more carbon, the
less heat.

Case Hardening. — This is a process for adding
more carbon to the surface of a piece of steel, so that
it will have good wear-resisting qualities, while being
tough and strong on the inside. It has the effect of
forming a very hard and durable skin on the surface
of soft steel, leaving the inside unaffected.

The simplest way, although not the most efficient,
is to heat the piece to be case hardened to a red
heat and then sprinkle or rub the part of the surface
to be hardened with potassium ferrocyanide. This
material is a deadly poison and should be handled
with care. Allow the cyanide to fuse on the surface
of the metal and then plunge into water, brine or
mercury. Eepeating the process makes the surface
harder and the hard skin deeper each time.

Another method consists of placing the piece to
be hardened in a bed of powdered bone (bone which
has been burned and then powdered) and cover with
more powdered bone, holding the whole in an iron
tray. Now heat the tray and bone with the work
in an oven to a bright red heat for 30 minutes to an
hour and then plunge the work into water or brine.

CHAPTER II

OXY-ACETYLENE WELDING AND CUTTING
MATERIALS

Welding. — Oxy-acetylene welding is an autogenous
welding process, in which two parts of the same or
different metals are joined by causing the edges to
melt and unite while molten without the aid of
hammering or compression. When cool, the parts
form one piece of metal.

The oxy-acetylene flame is made by mixing oxygen
and acetylene gases in a special welding torch or
blowpipe, producing, when burned, a heat of 6,300
degrees, which is more than twice the melting tem-
perature of the common metals. This flame, while
being of intense heat, is of very small size.

Cutting. — The process of cutting metals with the
flame produced from oxygen and acetylene depends
on the fact that a jet of oxygen directed upon hot
metal causes the metal itself to burn away with great
rapidity, resulting in a narrow slot through the sec-
tion cut. The action is so fast that metal is not in-
jured on either side of the cut.

Carbon Removal. — This process depends on the
fact that carbon will burn and almost completely
vanish if the action is assisted with a supply of pure
oxygen gas. After the combustion is started with
any convenient flame, it continues as long as carbon
remains in the path of the jet of oxygen.

Materials. — For the performance of the above oper-
ations we require the two gases, oxygen and acetylene,
to produce the flames; rods of metal which may be
added to the joints while molten in order to give

33

34 WELDING

the weld sufficient strength and proper form, and va-
rious chemical powders, called fluxes, which assist
in the flow of metal and in doing away with many
of the impurities and other objectionable features.

Instruments. — To control the combustion of the
gases and add to the convenience of the operator a
number of accessories are required.

The pressure of the gases in their usual containers
is much too high for their proper use in the torch
and we therefore need suitable valves which allow the
gas to escape from the containers when wanted, and
other specially designed valves which reduce the
pressure. Hose, composed of rubber and fabric, to-
gether with suitable connections, is used to carry the
gas to the torch.

The torches for welding and cutting form a class of
highly developed instruments of the greatest accuracy
in manufacture, and must be thoroughly understood
by the welder. Tables, stands and special supports
are provided for holding the work while being welded,
and in order to handle the various metals and allow
for their peculiarities while heated use is made of
ovens and torches for preheating. The operator re-
quires the protection of goggles, masks, gloves and
appliances which prevent undue radiation of the heat.

Torch Practice. — The actual work of welding and
cutting requires preliminary preparation in the form
of heat treatment for the metals, including preheat-
ing, annealing and tempering. The surfaces to be
joined must be properly prepared for the flame, and
the operation of the torches for best results requires
careful and correct regulation of the gases and the
flame produced.

Finally, the different metals that are to be welded

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 35

require special treatment for each one, depending on
the physical and chemical characteristics of the ma-
terial.

It will thus be seen that the apparently simple
operations of welding and cutting require special
materials, instruments and preparation on the part
of the operator and it is a proved fact that failures,
which have been attributed to the method, are really
due to lack of these necessary qualifications.
OXYGEN

Oxygen, the gas which supports the rapid combus-
tion of the acetylene in the torch flame, is one of
the elements of the air. It is the cause and the active
agent of all combustion that takes place in the at-
mosphere. Oxygen was first discovered as a separate
gas in 1774, when it was produced by heating red
oxide of mercury and was given its present name by
the famous chemist, Lavoisier.

Oxygen is prepared in the laboratory by various
methods, these including the heating of chloride of
lime and 'peroxide of cobalt mixed in a retort, the
heating of chlorate of potash, and the separation of
water into its elements, hydrogen and oxygen, by the
passage of an electric current. While the last process
is used on a large scale in commercial work, the
others are not practical for work other than that of
an experimental or temporary nature.

This gas is a colorless, odorless, tasteless element.
It is sixteen times as heavy as the gas hydrogen when
measured by volume under the same temperature and
pressure. Under all ordinary conditions oxygen
remains in a gaseous form, although it turns to a
liquid when compressed to 4,400 pounds to the square
inch and at a temperature of 220° below zero.

36 WELDING

Oxygen unites with almost every other element,
this union often taking place with great heat and
much light, producing flame. Steel and iron will
burn rapidly when placed in this gas if the combus-
tion is started with a flame of high heat playing on
the metal. If the end of a wire is heated bright red
and quickly plunged into a jar containing this gas,
the wire will burn away with a dazzling light and be
entirely consumed except for the molten drops that
separate themselves. This property of oxygen is used
in oxy-acetylene cutting of steel.

The combination of oxygen with other substances
does not necessarily cause great heat, in fact the com-
bination may be so slow and gradual that the change
of temperature can not be noticed. An example of
this slow combustion, or oxidation, is found in the'
conversion of iron into rust as the metal combines
with the active gas. The respiration of human beings
and animals is a form of slow combustion and is the
source of animal heat. It is a general rule that the
process of oxidation takes place with increasing rapid-
ity as the temperature of the body being acted upon
rises. Iron and steel at a red heat oxidize rapidly
with the formation of a scale and possible damage to
the metal.

Air. — Atmospheric air is a mixture of oxygen and
nitrogen with traces of carbonic acid gas and water
vapor. Twenty-one per cent of the air, by volume,
is oxygen and the remaining seventy-nine per cent
is the inactive gas, nitrogen. But for the presence
of the nitrogen, which deadens the action of the other
gas, combustion would take place at a destructive
rate and be beyond human control in almost all cases.
These two gases exist simply as a mixture to form the

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 37

air and are not chemically combined. It is there-
fore a comparatively simple matter to separate them
with the processes now available.

Water. — Water is a combination of oxygen and
hydrogen, being composed of exactly two volumes of
hydrogen to one volume of oxygen. If these two gases

Figure 7. — Obtaining Oxygen by Electrolysis

be separated from each other and then allowed to
mix in these, proportions they unite with explosive
violence and form water. Water itself may be sepa-
rated into the gases by any one of several means,
one making use of a temperature of 2,200° to bring
about this separation.

The easiest way to separate water into its two parts
is by the process called electrolysis (Figure 7). Water,

38 WELDING

with which has been mixed a small quantity of acid,
is placed in a vat through the walls of which enter the
platinum tipped ends of two electrical conductors, one
positive and the other negative.

Tubes are placed directly above these wire ter-
minals in the vat, one tube being over each electrode
and separated from each other by some distance.
With the passage of an electric current from one wire
terminal to the other, bubbles of gas rise from each
and pass into the tubes. The gas that comes from
the negative terminal is hydrogen and that from
the positive pole is oxygen, both gases being almost
pure if the work is properly conducted. This method
produces electrolytic oxygen and electrolytic hydro-
gen.

The Liquid Air Process. — While several of the
foregoing methods of securing oxygen are success-
ful as far as this result is concerned, they are not
profitable from a financial standpoint. A process
for separating oxygen from the nitrogen in the air
has been brought to a high state of perfection and is
now supplying a major part of this gas for oxy-
acetylene welding. It is known as the Linde process
and the gas is distributed by the Linde Air Products
Company from its plants and warehouses located in
/the large cities of the country.

The air is first liquefied by compression, after which
the gases are separated and the oxygen collected. The
air is purified and then compressed by successive
stages in powerful machines designed for this pur-
pose until it reaches a, pressure of about 3,000 pounds
to the square inch. The large amount of heat pro-
duced is absorbed by special coolers during the
process of compression. The highly compressed air is

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 39

then dried and the temperature further reduced by
other coolers.

The next point in the separation is that at which
the air is introduced into an apparatus called an in-
terchanger and is allowed to escape through a valve,
causing it to turn to a liquid. This liquid air is
sprayed onto plates and as it falls, the nitrogen re-
turn to its gaseous state arid leaves the oxygen to
run to the bottom of the container. This liquid
oxygen is then allowed to return to a gas and is
stored in large gasometers or tanks.

The oxygen gas is taken from the storage tanks and
compressed to approximately 1,800 pounds to the
square inch, under which pressure it is passed into
steel cylinders and made ready for delivery to the
customer. This oxygen is guaranteed to be ninety-
seven per cent pure.

Another process, known as the Hildebrandt process,
is coming into use in this country. It is a later process
and is used in Germany to a much greater extent than
the Linde process. The Superior Oxygen Co. has
secured the American rights and has established sev-
eral plants.

Oxygen Cylinders. — Two sizes of cylinders are in
use, one containing 100 cubic feet of gas when it is
at atmospheric pressure and the other containing 250
cubic feet under similar conditions. The cylinders
are made from one piece of steel and are without
seams. These containers are tested at double the pres-
sure of the gas contained to insure safety while
handling.

One hundred cubic feet of oxygen weighs nearly
nine pounds (8.921), and therefore the cylinders
will we:'""1"1 fVally nine pounds more when full

40 WELDING

than after emptying, if of the 100 cubic feet size.
The large cylinders weigh about eighteen and one-
quarter pounds more when full than when empty,
making approximately 212 pounds empty and 230
pounds full.

The following table gives the number of cubic feet
of oxygen remaining in the cylinders according to
various gauge pressures from an initial pressure of
1,800 pounds. The amounts given are not exactly
correct as this would necessitate lengthy calculations
which would not make great enough difference to
affect the practical usefulness of the table :

Cylinder of 100 Cu. Ft. Capacity at 68° Fahr.

Gauge Volume Gauge Volume

Pressure Remaining Pressure Remaining

1800 100 700 39

1620 90 500 28

1440 80 300 17

1260 70 100 6

1080 60 18 1

900 50 9 %

Cylinder of 250 Cu. Ft. Capacity at 68° Fahr.

Gauge Volume Gauge Volume

Pressure Remaining Pressure Remaining

1800 250 700 9-7

1620 225 500 70

1440 200 300 42

1260 175 100 15

1080 150 18 8

900 125 9 1%

The temperature of the cylinder affects the pressure
in a large degree, the pressure increasing with a rise
in temperature and falling with a fall in temperature.
The variation for a 100 cubic foot cylinder at various
temperatures is given in the following tabulation :

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 41

At 150° Fahr 2090 pounds.

At 100° Fahr 1912 pounds.

At 80° Fahr 1844 pounds.

At 68° Fahr 1800 pounds.

At 50° Fahr 1736 pounds.

At 32° Fahr 1672 pounds.

At 0 Fahr 1558 pounds.

At — 10° Fahr 1522 pounds.

Chlorate of Potash Method. — In spite of its higher
cost and the inferior gas produced, the chlorate of
potash method of producing oxygen is used to a

N

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rs

[=jj RETORT

7

£Z2

wsA Y///A

&UA

^

<OOA

h -i

Hi

—

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=.

ii

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s

—

ZE

IE:

GASOMETER

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Figure 8. — Oxygen from Chlorate of Potash

limited extent when it is impossible to secure the gas
in cylinders.

An iron retort (Figure 8) is arranged to receive
about fifteen pounds of chlorate of potash mixed with
three pounds of manganese dioxide, after which the
cylinder is closed with a tight cap, clamped on. This
retort is carried above a burner using fuel gas or
other means of generating heat and this burner is
lighted after the chemical charge is mixed and com-
pressed in the tube.

The generation of gas commences and the oxygen is
led through water baths which wash and cool it

42 WELDING

before storing in a tank connected with the plant.
From this tank the gas is compressed into portable
cylinders at a pressure of about 300 pounds to the
square inch for use as required in welding operations.

Each pound of chlorate of potash liberates about
three cubic feet of oxygen, and taking everything into
consideration, the cost of gas produced in this way is
several times that of the purer product secured by
the liquid air process.

These chemical generators are oftentimes a source
of great danger, especially when used with or near
the acetylene gas generator, as is sometimes the case
with cheap portable outfits. Their use should not be
tolerated when any other method is available, as the
danger from accident alone should prohibit the prac-
tice except when properly installed and cared for
away from other sources of combustible gases.

ACETYLENE

In 1862 a chemist, Woehler, announced the dis-
covery of the preparation of acetylene gas from cal-
cium carbide, which he had made by heating to a high
temperature a mixture of charcoal with an alloy of
zinc and calcium. His product would decompose
water and yield the gas. For nearly thirty years these
substances were neglected, with the result that acety-
lene was practically unknown, and up to 1892 an
acetylene flame was seen by very few persons and
its possibilities were not dreamed of. "With the de-
velopment of the modern electric furnace the possi-
bility of calcium carbide as a commercial product
became known.

In the above year, Thomas L. "Willson, an electrical
engineer of Spray, North Carolina, was experiment-

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 43

ing in an attempt to prepare metallic calcium, for
which purpose he employed an electric furnace oper-
ating on a mixture of lime and coal tar with about
ninety-five horse power. The result was a molten
mass which became hard and brittle when cool. This
apparently useless product was discarded and thrown
in a nearby stream, when, to the astonisment of on-
lookers, a large volume of gas was immediately lib-
erated, which, when ignited, burned with a bright
and smoky flame and gave off quantities of soot.
The solid material proved to be calcium carbide and
the gas acetylene.

Thus, through the incidental study of a by-product,
and as the result of an accident, the possibilities in
carbide were made known, and in the spring of 1895
the first factory in the world for the production of
this substance was established by the Willson Alumi-
num Company.

When water and calcium carbide are brought to-
gether an action takes place which results in the for-
mation of acetylene gas and slaked lime.

CARBIDE

Calcium carbide is a chemical combination of the
elements carbon and calcium, being dark brown, black
or gray with sometimes a blue or red tinge. It
looks like stone and will only burn when heated with
oxygen.

Calcium carbide may be preserved for any length
of time if protected from the air, but the ordinary
moisture in the atmosphere gradually affects it until
nothing remains but slaked lime. It always possesses
a penetrating odor, which is not due to the carbide
itself but to the fact that it is being constantly af-

44 WELDING

fected by moisture and producing small quantities of
acetylene gas.

This material is not readily dissolved by liquids,
but if allowed to come in contact with water, a de-
composition takes place with the evolution of large
quantities of gas. Carbide is not affected by shock,
jarring or age.

A pound of absolutely pure carbide will yield five
and one-half cubic feet of acetylene. Absolute purity
cannot be attained commercially, and in practice good
carbide will produce from four and one-half to five
cubic feet for each pound used.

Carbide is prepared by fusing lime and carbon in
the electric furnace under a heat in excess of 6,000°
Fahrenheit. These materials are among the most diffi-
cult to melt that are known. Lime is so infusible that
it is frequently employed for the materials of cruci-
bles in which the highest melting metals are fused,
and for the pencils in the calcium light because it will
stand extremely high temperatures.

Carbon is the material employed in the manufac-
ture of arc light electrodes and other electrical appli-
ances that must stand extreme heat. Yet these two
substances are forced into combination in the manu-
facture of calcium carbide. It is the excessively high
temperature attainable in the electric furnace that
causes this combination and not any effect of the elec-
tricity other than the heat produced.

A mixture of ground coke and lime is introduced
into the furnace through which an electric arc has
been drawn. The materials unite and form an ingot
of very pure carbide surrounded by a crust of less
purity. The poorer crust is rejected in breaking up
the mass into lumps which are graded according to

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 45

their size. The largest size is 2 by 3y2 inches and
is called "lump," a medium size is y2 by 2 inches and
is called ' ' egg, ' ' an intermediate size for certain types
of generators is % by 1^4 inches and called "nut,"
and the finely crushed pieces for use in still other
types of generators are 1/12 by 14 inch in size and
are called "quarter." Instructions as to the size best
suited to different generators are furnished by the
makers of those instruments.

These sizes are packed in air-tight sheet steel drums
containing 100 pounds each. The Union Carbide
Company of Chicago and New York, operating under
patents, manufactures and distributes the supply of
calcium carbide for the entire United States. Plants
for this manufacture are established at Niagara Falls,
New York, and Sault Ste. Marie, Michigan. This
company maintains a system of warehouses in more
than one hundred and ten cities, where large stocks
of all sizes are carried.

The National Board of Fire Underwriters gives the
following rules for the storage of carbide:

Calcium carbide in quantities not to exceed six
hundred pounds may be stored, when contained in
approved metal packages not, to exceed one hundred
pounds each, inside insured property, provided that
the place of storage be dry, waterproof and well ven-
tilated and also provided that all but one of the
packages in any one building shall be sealed and
that seals shall not be broken so long as there is car-
bide in excess of one pound in any other unsealed
package in the building.

Calcium carbide in quantities in excess of six hun-
dred pounds must be stored above ground in detached
buildings, used exclusively for the storage of cal-

46 WELDING

cium carbide, in approved metal packages, and such
buildings shall be constructed to be dry, waterproof
and well ventilated.

Properties of Acetylene. — This gas is composed of
twenty-four parts of carbon and two parts of hydro-
.gen by weight and is classed with natural gas, petro-
leum, etc., as one of the hydrocarbons. This gas con-
tains the highest percentage of carbon known to exist
in any combination of this form and it may there-
fore be considered as gaseous carbon. Carbon is the
fuel that is used in all forms of combustion and is
present in all fuels from whatever source or in what-
ever form. Acetylene is therefore the most power-
ful of all fuel gases and is able to give to the torch
flame in welding the highest temperature of any
flame.

Acetylene is a colorless and tasteless gas, possessed
of a peculiar and penetrating odor. The least trace
in the air of a room is easily noticed, and if this odor
is detected about an apparatus in operation, it is
certain to indicate a leakage of gas through faulty
piping, open valves, broken hose or otherwise. This
leakage must be prevented before proceeding with the
work to be done.

All gases which burn in air will, when mixed with
air previous to ignition, produce more or less vio-
lent explosions, if fired. To this rule acetylene is no
exception. One measure of acetylene and twelve and
one-half of air are required for complete combustion ;
this is therefore the proportion for the most perfect
explosion. This is not the only possible mixture that
will explode, for all proportions from three to thirty
per cent of acetylene in air will explode with more
or less force if ignited.

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 47

The igniting point of acetylene is lower than that
of coal gas, being about 900 degrees Fahrenheit as
against eleven hundred degrees for coal gas. The
gas issuing from a torch will ignite if allowed to play
on the tip of a lighted cigar.

It is still further true that acetylene, at some pres-
sures, greater than normal, has under most favorable
conditions for the effect, been found to explode ; yet
it may be stated with perfect confidence that under no
circumstances has anyone ever secured an explosion
in it when subjected to pressures not exceeding fif-
teen pounds to the square inch.

Although not exploded by the application of high
heat, acetylene is injured by such treatment. It is
partly converted, by high heat, into other compounds,
thus lessening the actual quantity of the gas, wasting
it and polluting the rest by the introduction of sub-
stances which do not belong there. These compounds
remain in part with the gas, causing it to burn with
a persistent smoky flame and with the deposit of
objectionable tarry substances. Where the gas is gen-
erated without undue rise of temperature these diffi-
culties are avoided.

Purification of Acetylene. — Impurities in this gas
are caused by impurities in the calcium carbide from
which it is made or by improper methods and lack of
care in generation. Impurities from the material
will be considered first.

Impurities in the carbide may be further divided
into two classes: those which exert no action on wrater
and those which act with the water to throw off
other gaseous products which remain in the acetylene.
Those impurities which exert no action on the water
consist of coke that has not been changed in the

48 WELDING

furnace and sand and some other substances which
are harmless except that they increase the ash left
after the acetylene has been generated.

An analysis of the gas coming from a typical gen-
erator is as follows:

Per cent

Acetylene 99.36

Oxygen 08

Nitrogen 11

Hydrogen 06

Sulphuretted Hydrogen . 17

Phosphoretted Hydrogen 04

Ammonia 10

Silicon Hydride 03

Carbon Monoxide 01

Methane 04

The oxygen, nitrogen, hydrogen, methane and car-
bon monoxide are either harmless or are present in
such small quantities as to be neglected. The phos-
phoretted hydrogen and silicon hydride are self-
inflammable gases when exposed to the air, but their
quantity is so very small that this possibility may be
dismissed. The ammonia and sulphuretted hydrogen
are almost entirely dissolved by the water used in
the gas generator. The surest way to avoid impure
gas is to use high-grade calcium carbide in the gener-
ator and the carbide of American manufacture is
now so pure that it never causes trouble.

The first and most important purification to which
the gas is subjected is its passage through the body
of water in the generator as it bubbles to the top.
It is then filtered through felt to remove the solid

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 49

particles of lime dust and other impurities which
float in the gas.

Further purification to remove the remaining am-
monia, sulphuretted hydrogen and phosphorus con-
taining compounds is accomplished by chemical
means. If this is considered necessary it can be easily
accomplished by readily available purifying appa-
ratus which can be attached to any generator or in-
serted between the generator and torch outlets. The
following mixtures have been used.

"Heratol," a solution of chromic acid or sulphuric
acid absorbed in porous earth.

"Acagine," a mixture of bleaching powder with
fifteen per cent of lead chromate.

"Puratylene," a mixture of bleaching powder and
hydroxide of lime, made very porous, and containing
from eighteen to twenty per cent of active chlorine.

"FrQnkoline," a mixture of cuprous and ferric
chlorides dissolved in strong hydrochloric acid ab-
sorbed in infusorial earth.

A test for impure acetylene gas is made by placing
a drop of ten per cent solution of silver nitrate on
a white blotter and holding the paper in a stream of
gas coming from the torch tip. Blackening of the
paper in a short length of time indicates impurities.

Acetylene in Tanks. — Acetylene is soluble in water
to a very limited extent, too limited to be of prac-
tical use. There is only one liquid that possesses
sufficient power of containing acetylene in solution
to be of commercial value, this being the liquid ace-
tone. Acetone is produced in various ways, often-
times from the distillation of wood. It is a trans-
parent, colorless liquid that flows with ease. It boils
at 133° Fahrenheit, is inflammable and burns with

50 WELDING

a luminous flame. It has a peculiar but rather agree-
able odor.

Acetone dissolves twenty-four times its own bulk of
acetylene at ordinary atmospheric pressure. If this
pressure is increased to two atmospheres, 14.7 pounds
above ordinary pressure, it will dissolve just twice as
much of the gas and for each atmosphere that the
pressure is increased it will dissolve as much more.

If acetylene be compressed above fifteen pounds
per square inch at ordinary temperature without first
being dissolved in acetone a danger is present of self-
ignition. This danger, while practically nothing at
fifteen pounds, increases with the pressure until at
forty atmospheres it is very explosive. Mixed with
acetone, the gas loses this dangerous property and is
safe for handling and transportation. As acetylene is
dissolved in the liquid the acetone increases its vol-
ume slightly so that when the gas has been drawn out
of a closed tank a space is left full of free acetylene.

This last difficulty is removed by first filling the
cylinder or tank with some porous material, such as
asbestos, wrood charcoal, infusorial earth, etc. As-
bestos is used in practice and by a system of packing
and supporting the absorbent material no space is
left for the free gas, even when the acetylene has.
been completely withdrawn.

The acetylene is generated in the usual way and is
washed, purified and dried. Great care is used to
make the gas as free as possible from all impurities
and from air. The gas is forced into containers
filled with acetone as described and is compressed to
one hundred and fifty pounds to the square inch.
From these tanks it is transferred to the smaller port-
able cvlinders for consumers ' use.

OXY-ACETYLBNE WELDING AND CUTTING MATERIALS 51

The exact volume of gas remaining in a cylinder at
atmospheric temperature may be calculated if the
weight of the cylinder empty is known. One pound
of the gas occupies 13.6 cubic feet, so that if the
difference in weight between the empty cylinder and
the one considered be multiplied by 13.6, the result
will be the number of cubic feet of gas contained.

The cylinders contain from 100 to 500 cubic feet
of acetylene under pressure. They cannot be filled
with the ordinary type of generator as they require
special purifying and compressing apparatus, which
should never be installed in any building where other
work is being carried on, or near other buildings
which are occupied, because of the danger of ex-
plosion.

Dissolved acetylene is manufactured by the Prest-
0-Lite Company, the Commercial Acetylene Com-,
pany and the Searchlight Gas Company and is dis-
tributed from warehouses in various cities.

These tanks should not be discharged at a rate per
hour greater than one-seventh of their total capacity,
that is, from a tank of 100 cubic feet capacity, the
discharge should not be more than fourteen cubic
feet per hour. If discharge is carried on at an ex-
cessive rate the acetone is drawn out with the
and reduces the heat of the welding flame.

For this reason welding should not be attempted
with cylinders designed for automobile and boat
lighting. When the work demands a greater delivery
than one of the larger tanks will give, two or more
tanks may be connected with a special coupler such as
may be secured from the makers and distributers of
the gas. These couplers may be arranged for two,
three, four or five tanks in one battery by removing

52 WELDING

the plugs on the body of the coupler and attaching
additional connecting pipes. The coupler body car-
ries a pressure gauge and the valve for controlling
the pressure of the gas as it flows to the welding
torches. The following capacities should be provided
for:

Acetylene Consumption Combined Capacity of

of Torches per Hour Cylinders in Use

Up to 15 feet 100 cubic feet

16 to 30 feet 200 cubic feet

31 to 45 feet 300 cubic feet

46 to 60 feet 400 cubic feet

61 to 75 feet 500 cubic feet

WELDING RODS

The best welding cannot be done without using the
best grade of materials, and the added cost of these
materials over less desirable forms is so slight when
compared to the quality of work performed and the
waste of gases with inferior supplies, that it is very
unprofitable to take any chances in this respect. The
makers of welding equipment carry an assortment of
supplies that have been standardized and that may
be relied upon to produce the desired result when
properly used. The safest plan is to secure this class
of material from the makers.

"Welding rods, or welding sticks, are used to supply
the additional metal required in the body of the weld
to replace that broken or cut away and also to add
to the joint whenever possible so that the work may
have the same or greater strength than that found in
the original piece. A rod of the same material as

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 53

that being welded is used when both parts of the work
are the same. When dissimilar metals are to be joined x
rods of a composition suited to the work are em-
ployed.

These filling rods are required in all work except
steel of less than 16 gauge. Alloy iron rods are usedV
for cast iron. These rods have a high silicon content,
the silicon reacting with the carbon in the iron to
produce a softer and more easily machined weld than
would otherwise be the case. These rods are often
made so that they melt at a slightly lower point than
cast iron. This is done for the reason that when the
part being welded has been brought to the fusing heat
by the torch, the filling material can be instantly
melted in without allowing the parts to cool. The
metal can be added faster and more easily controlled.

Rods or wires of Jforwyron are used for steel

^

welding in almost all cases. The purity of this grade 1
of iron gives a homogeneous, soft weld of even texture,
great ductility and exceptionally good machining
qualities. For welding heavy steel castings, a rod of
rolled carbon steel is employed. For working on high
carbon steel, a rod of the steel being welded must be
employed and for alloy steels, such as nickel, man-
ganese, vanadium, etc., special rods of suitable alloy
composition are preferable.

Aluminum welding rods are made from this metal

alloyed to give the even flowing that is essential.

< Aluminum is one of the most difficult of all the metals

to handle in this work and the selection of the proper

rod is of great importance.

Brass is filled with brass wire when in small cast-
ings and sheets. For general work with brass castings,
manganese bronze or Tobin bronze may be used.

54 WELDING

Bronze is welded with manganese bronze or Tobin
bronze, while copper is filled with copper wire.

These welding rods should always be used to fill
the weld when the thickness of material makes their
employment necessary, and additional metal should
always be added at the weld when possible as the
joint cannot have the same strength as the original
piece if made or dressed off flush with the surfaces
around the weld. This is true because the metal
welded into the joint is a casting and will never have
more strength than a casting of the material used for
filling.

Great care should be exercised when adding metal
from welding rods to make sure that no metal is
added at a point that is not itself melted and molten
when the addition is made. When molten metal is
placed upon cooler siirfaces the result is not a weld
but merely a sticking together of the two parts with-
out any strength in the joint.

FLUXES

Difficulty would be experienced in welding with
only the metal and rod to work with because of the
scale that forms on many materials under heat, the
oxides of other metals and the impurities found in
almost all metals. These things tend to prevent a
perfect joining of the metals and some means are
necessary to prevent their action.

Various chemicals, usually in powder form, are
used to accomplish the result of cleaning the weld
and making the work of the operator less difficult.
They are called fluxes.

^ A flux is used to float off physical impurities from
the molten metal; to furnish a protecting coating

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 55

around the weld ; to assist in the removal of any ob-
jectionable oxide of the metals being handled ; to
lower the temperature at which the materials flow ; to
make a cleaner weld and to produce a better quality
of metal in the finished work.

The flux must be of such composition that it will
accomplish the desired result without introducing
new difficulties. They may be prepared by the oper-
ator in many cases or may be secured from the mak-
ers of welding apparatus, the same remarks applying
to their quality as were made regarding the welding
rods, that is, only the best should be considered.
4-The flux used for cast iron should have a softening
effect and should prevent burning of the metal. In
many cases it is possible and even preferable to weld
cast iron without the use of a flux, and in any event
the smaller the quantity used the better the result
should be. Flux should not be added just before the
completion of the work because the heat will not have
time to drive the added elements out of the metal or
to incorporate them with the metal properly.

/Aluminum should never be welded without using
a flux because of the oxide formed. This oxide, called
alumina, does not melt until a heat of 5,000° Fahren-
heit is reached, four times the heat needed to melt the
aluminum itself. It is necessary that this oxide be
broken down or dissolved so that the aluminum may
have a chance to flow together. Copper is another
metal that requires a flux because of its rapid, oxida-
tion under heat.

While the flux is often thrown or sprinkled along
the break while welding, much better results will be
obtained by dipping the hot end of the welding rod
into the flux whenever the work needs it. Suffi-

56 WELDING

cient powder will stick on the end of the rod for all
) purposes, and with some fluxes too much will adhere.
Care should always be used to avoid the application
of excessive flux, as this is usually worse than using
too little.

SUPPLIES AND FIXTURES

Goggles. — The oxy-acetylene torch should not be
used without the protection to the eyes afforded by
goggles. These not only relieve unnecessary strain,
but make it much easier to watch the exact progress
of the work with the molten metal The difficulty of
protecting the sight while welding is even greater
than when cutting metal with the torch.

Acetylene gives a light which is nearest to sunlight
of any artificial illuminant. But for the fact that
this gas light gives a little more green and less blue
in its composition, it would be the same in quality
and practically the same in intensity. This light
from the gas is almost abseqt during welding, being
lost with the addition of the) extra oxygen needed to
produce the welding heat. * The light that is dan-
gerous comes from the molten metal which flows
under the torch at a bright white heat.

Goggles for protection against this light and the
heat that goes with it may be secured in various
tints, the darker glass being for welding and the
lighter for cutting. Those having frames in which
the metal parts do not touch the flesh directly are
most desirable because of the high temperature
reached by these parts.

Gloves. — While not as necessary as are the goggles,
gloves are a convenience in many cases. Those in
which leather touches the hands directly are really

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 57

of little value as the heat that protection is desired
against makes the leather so hot that nothing is gained
in comfort. Gloves are made with asbestos cloth,
which are not open to this objection in so great a
degree.

Figure 9. — Frame for Welding Stand

Tables and Stands. — Tables for holding work while
being welded (Figure 9) are usually made from
lengths of angle steel welded together. The top should
be rectangular, about two feet wide and two and one-
half feet long. The legs should support the working
surface at a height of thirty-two to thirty-six inches
from the floor. Metal lattice work may be fastened
or laid in the top framework and used to support a
layer of firebrick bound together with a mixture of
one-third cement and two-thirds fireclay. The piece
being welded is braced and supported on this table
with pieces of firebrick so that it will remain station-
ary during the operation.

58 WELDING

Holders for supporting the tanks of gas may be
made or purchased in forms that rest directly on the
floor or that are mounted on wheels. These holders
are quite useful where the floor or ground is very
uneven.

Hose. — All permanent lines from tanks and gener-
ators to the torches are made with piping rigidly sup-
ported, but the short distance from the end of the
pipe line to the torch itself is completed with a flexi-
ble hose so that the operator may be free in his move-
ments while welding. An accident through which the
gases mix in the hose and are ignited will burst this
part of the equipment, with more or less painful re-
sults to the person handling it. For that reason it is
well to use hose with great enough strength to with-
stand excessive pressure.

A poor grade of hose will also break down inside
and clog the flow of gas, both through itself and
through the parts of the torch. To avoid outside dam-
age and cuts this hose is sometimes encased with
coiled sheet metal. Hose may be secured with a burst-
ing strength of more than 1,000 pounds to the square
inch. Many operators prefer to distinguish between
the oxygen and acetylene lines by their color and to
allow this, red is used for the oxygen, and bla£k_Jor
acetylene.

Other Materials. — Sheet asbestos and asbestos fibre
in flakes are used to cover parts of the work while pre-
paring them for welding and during the operation
kself. The flakes and small pieces that become de-
tached from the large sheets are thrown into a bin
where the completed small work is placed to allow
slow and even cooling while protected by the asbestos.

Asbestos fibre and also ordinary fireclay are often

OXY-ACETYLENE WELDING AND CUTTING MATERIALS 59

used to make a backing or mould into a form that
may be placed behind aluminum and some other
metals that flow at a low heat and which are accord-
ingly difficult to handle under ordinary methods.
This forms a solid mould into which the metal is prac-
tically cast as melted by the torch so that the desired
shape is secured without danger of the walls of metal
breaking through and flowing away.

Carbon blocks and rods are made in various shapes
and sizes so that they may be -used to fill threaded
holes and other places that it is desired to protect
during welding. These may be secured in rods of
various diameters up to one inch and in blocks of
several different dimensions.

CHAPTER III
ACETYLENE GENERATORS

Acetylene generators used for producing the gas
from the action of water on calcium carbide are di-
vided into three principal classes according to the
pressure under which they operate.

Low pressure generators are designed to operate at
one pound or less per square inch. Medium pressure
systems deliver the gas at not to exceed fifteen pounds
to the square inch while high pressure types furnish
gas above fifteen pounds per square inch. High
pressure systems are almost unknown in this country,
the medium pressure type being often referred to as
"high pressure."

Another important distinction is formed by the
method of bringing the carbide and water together.
The majority of those now in use operate by drop-
ping small quantities of carbide into a large volume
of water, allowing the generated gas to bubble up
through the water before being collected above the
surface. This type is known as the "carbide to
water " generator.

A less used type brings a measured and small quan-
tity of water to a comparatively large body of the
carbide, the gas being formed and collected from
the chamber in which the action takes place. This
is called the "water to carbide77 type. Another way
of expressing the difference in feed is that of desig-
nating the two types as "carbide feed'7 for the former
and "water feed77 for the latter.

60

ACETYLENE GENERATORS 61

A further division of the carbide to water ma-
chines is made by mentioning the exact method of
feeding the carbide One type, called "gravity feed"
operates by allowing the carbide to escape and fall by
the action of its own weight, or gravity; the other
type, called "forced feed," includes a separate mech-
anism driven by power This mechanism feeds defi-
nite amounts of the carbide to the water as required
by the demands on the generator. The action of
either feed is controlled by the withdrawal of gas
from the generator, the aim being to supply suffi-
cient carbide to maintain a nearly constant supply.

Generator Requirements. — The qualities of a good
generator are outlined as follows :*

It must allow no possibility of the existence of an
explosive mixture in any of its parts at any time. It
is not enough to argue that a mixture, even if it exists,
cannot be exploded unless kindled. It is necessary to
demand that a dangerous mixture can at no time be
formed, even if the machine is tampered with by an
ignorant person. The perfect machine must be so
constructed that it shall be impossible at any time,
under any circumstances, to blow it up.

It must insure cool generation. Since this is a rela-
tive term, all machines being heated somewhat dur-
ing the generation of gas, this amounts to saying that
a machine must heat but little. A pound of carbide
decomposed by water develops the same amount of
heat under all circumstances, but that heat can be
allowed to increase locally to a high point, or it can
be equalized by water so that no part of the material
becomes heated enough to do damage.

r See Pond's "Calcium Carbide and Acetylene."

62 WELDING

It must be well constructed. A good generator
does not need, perhaps, to be ' ' built like a watch, ' ' but
it should be solid, substantial and of good material.
It should be built for service, to last and not simply
to sell; anything short of this is to be avoided as
unsafe and unreliable.

It must be simple. The more complicated the ma-
chine the sooner it will get out of order. Understand
your generator. Know what is inside of it and be-
ware of an apparatus, however attractive its exterior,
whose interior is filled with pipes and tubes, valves
and diaphragms whose functions you do not per-
fectly understand.

It should be capable of being cleaned and re-
charged and of receiving all other necessary atten-
tion without loss of gas, both for economy 's sake, and
more particularly to avoid danger of fire.

It should require little attention. All machines
have to be emptied and recharged periodically; but
the more this process is simplified and the more
quickly this can be accomplished, the better.

It should be provided with a suitable indicator to
designate how low the charge is in order that the
refilling may be done in good season.

It should completely use up the carbide, generat-
ing the maximum amount of gas.

Overheating. — A large amount of heat is liberated
when acetylene gas is formed from the union of cal-
cium carbide and water. Overheating during this
process, that is to say, an intense local heat rather
than a large amount of heat well distributed, brings
about the phenomenon of polymerization, converting
the gas, or part of it, into oily matters, which can do
nothing but harm. This tarry mass coming through

ACETYLENE GENERATORS 63

the small openings in the torches causes them to be-
come partly closed and alters the proportions of the
gases to the detriment of the welding flame. The only
remedy for this trouble is to avoid its cause and
secure cool generation.

Overheating can be detected by the appearance of
the sludge remaining after the gas has been made.
Discoloration, yellow or brown, shows that there has
been trouble in this direction and the resultant effects
at the torches may be looked for. The abundance of
water in the carbide to water machines effects this
cooling naturally and is a characteristic of well de-
signed machines of this class. It has been found best
and has practically become a fundamental rule of
generation that a gallon of water must be provided
for each pound of carbide placed in the generator.
With this ratio and a generator large enough for
the number of torches to be supplied, little trouble
need be looked for with overheating.

Water to Carbide Generators. — It is, of course,
much easier to obtain a measured and regular flow of
water than to obtain such a flow of any solid sub-
stance, especially when the solid substance is in the
form of lumps, as is carbide This fact led to the use
of a great many water-feed generators for all classes
of work, and this type is still in common use for the
small portable machines, such, for instance, as those
used on motor cars for the lamps. The water-feed
machine is not, however, favored for welding plants,
as is the carbide feed, in spite of the greater difficul-
ties attending the handling of the solid material.

A water-feed generator is made up of the gas pro-
ducing part and a holder for the acetylene after it
is made. The carbide is held in a tray formed of a

64 WELDING

number of small compartments so that the charge
in each compartment is nearly equal to that in each
of the others. The water is allowed to flow into one
of these compartments in a volume sufficient to pro-
duce the desired amount of gas and the carbide is
completely used from this one division. The water
then floods the first compartment and finally over-
flows into the next one, where the same process is
repeated. After using the carbide in this division,
it is flooded in turn and the water passing on to
those next in order, uses the entire charge of the
whole tray.

These generators are charged with the larger sizes
of carbide and are easily taken care of. The residue
is removed in the tray and emptied, making the gen-
erator ready for a fresh supply of carbide.

Carbide to Water Generators. — This type also is
made up of two principal parts, the generating cham-
ber and a gas holder, the holder being part of the
generating chamber or a separate device. The gen-
erator (Figure 10) contains a hopper to receive the
charge of carbide and is fitted with the feeding mech-
anism to drop the proper amount of carbide into the
water as required by the demands of the torches. The
charge of carbide is of one of the smaller sizes,
usually "nut" or "quarter."

Feed Mechanisms. — The device for dropping the
carbide into the water is the only part of the machine
that is at all complicated. This complication is
brought about by the necessity of controlling the
mass of carbide so that it can never be discharged
into the water at an excessive rate, feeding it at a
regular rate and in definite amounts, feeding it posi-
tively whenever required and shutting off the feed

ACETYLENE GENERATORS

65

just as positively when the supply of gas in the
holder is enough for the immediate needs.

The charge of carbide is unavoidably acted upon
by the water vapor in the generator and will in time

til

n «••••* O

become more or less pasty and sticky. This is more
noticeable if the generator stands idle for a consider-
able length of time This condition imposes another
duty on the feeding mechanism ; that is, the necessity
of self-cleaning so that the carbide, no matter in what

66 WELDING

condition, cannot prevent the positive action of this
part of the device, especially so that it cannot prevent
the supply from being stopped at the proper time.

The gas holder is usually made in the bell form
so that the upper portion rises and falls with the
addition to or withdrawal from the supply of gas
in the holder. The rise and fall of this bell is often
used to control the feed mechanism because this
movement indicates positively whether enough gas
has been made or that more is required. As the bell
lowers it sets the feed mechanism 'in motion, and
when the gas passing into the holder has raised the
bell a sufficient distance, the movement causes the
feed mechanism to stop the fall of carbide into the
water. In practice, the movement of this part of the
holder is held within very narrow limits.

Gas Holders. — No matter how1 close the adjustment
of the feeding device, there will always be a slight
amount of gas made after the fall of carbide is
stopped, this being caused by the evolution of gas
from the carbide with which water is already in con-
tact. This action is called " after generation" and
the gas holder in any type of generator must provide
sufficient capacity to accommodate this excess gas.
As a general rule the water -to carbide generator
requires a larger gas holder than the carbide to water
type because of the greater amount of carbide being
acted upon by the water at any one time, also be-
cause the surface of carbide presented to the moist
air within the generating chamber is greater with
this type.

Freezing. — Because of the rather large body of
water contained in any type of generator, there is
always danger of its freezing and rendering the

ACETYLENE GENERATORS 67

device inoperative unless placed in a temperature
above the freezing point of the water. It is, of
course, dangerous and against the insurarce rules to
place a generator in the same room with a fire of any
kind, but the room may be heated by steam or hot
water coils from a furnace in another building or
in another part of the same building.

When the generator is housed in a separate struc-
ture the walls should be made of materials or con-
struction that prevents the passage of heat or cold
through them to any great extent. This may be
accomplished by the use of hollow tile or concrete
blocks or by any other form of double wall providing
air spaces between the outer and inner facings. The
space between the parts of the wall may be filled with
materials that further retard the loss of heat if this
is necessary under the conditions prevailing.

Residue From Generators. — The sludge remaining
in the carbide to water generator may be drawn off
into the sewer if the piping is run at a slant great
enough to give a fall that carries the whole quantity,
both water and ash, away without allowing settling
and consequent clogging. Generators are provided
with agitators which are operated to stir the ash up
with the water so that the whole mass is carried off
when the drain cock is opened.

If sewer connections cannot be made in such a way
that the ash is entirely carried away, it is best to
run the liquid mass into a settling basin outside of
the building. This should be in the form of a shallow
pit which will allow the water to pass off by soaking
into the ground and by evaporation, leaving the
comparatively dry ash in the pit. This ash which
remains is essentially slaked lime and can often be

68 WELDING

disposed of to more or less advantage to be used in
mortar, whitewash, marking paths and any other use
for which slaked lime is suited. The disposition of
the ash depends entirely on local conditions. An
average analysis of this ash is as follows :

Sand 1.10 per cent.

Carbon 2.72

Oxide of iron and alumina. . 2.77

Lime 64.06

Water and carbonic acid. . . 29.35 "

Toooo

GENERATOR CONSTRUCTION

The water for generating purposes is carried in the
large tank-like compartment directly below the car-
bide chamber. See Figure 11. This water compart-
ment is filled through a pipe of such a height that
the water level cannot be brought above the proper
point or else the water compartment is provided with
a drain connection which accomplishes this same re-
sult by allowing an excess to flow away.

The quantity of water depends on the capacity of
the generator inasmuch as there must be one gallon
for each pound of carbide required. The generator
should be of sufficient capacity to furnish gas under
working conditions from one charge of carbide to all
torches installed for at least five hours continuous
use.

After calculating the withdrawal of the whole
number of torches according to the work they are
to do for this period of five hours the proper gen-

ACETYLENE GENERATORS 69

erator capacity may be found on the basis of one
cubic foot of gas per hour for each pound of carbide.
Thus if the torches were to use sixty cubic feet of
gas per hour, five hours would call for three hundred
cubic feet and a three hundred pound generator
should be installed. Generators are rated according
to their carbide capacity in pounds.

Charging. — The carbide capacity of the generator
should be great enough to furnish a continuous sup-
ply of gas for the maximum operating time, basing
the quantity of gas generated on four and one-half
cubic feet from each pound of lump carbide and on
four cubic feet from each pound of quarter, inter-
mediate sizes being in proportion.

Generators are built in such a way that it is impos-
sible for the- acetylene to escape from the gas holding:
compartment during the recharging process. This
is accomplished (1) by connecting the water inlet
pipe opening with a shut off valve in such a way
that the inlet cannot be uncovered or opened without
first closing the shut off valve with the same move-
ment of the operator; (2) by incorporating an auto-
matic or hydraulic one-way valve so that this valve
closes and acts as a check when the gas attempts to
flow from the holder back to the generating chamber,
or by any other means that will positively accomplish
this result.

In generators having no separate gas holding
chamber but carrying the supply in the same com-
partment in which it is generated, the gas contained
under pressure is allowed to escape through vent
pipes into the outside air before recharging with
carbide. As in the former case, the parts are so
interlocked that it is impossible to introduce carbide

70 WELDING

or water without first allowing the escape of the gas
in the generator.

It is required by the insurance rules that the entire
change of carbide while in the generator be held in
such a way that it may be entirely removed without
difficulty in case the necessity should arise.

Generators should be cleaned and recharged at
regular stated intervals. This work should be done
during daylight hours only and likewise all repairs
should be made at such a time that artificial light
is not needed. Where it is absolutely necessary to
use artificial light it should be provided only by
incandescent electric lamps enclosed in gas tight
globes.

In charging generating chambers the old ash and
all residue must first be cleaned out and the operator
should be sure that no drain or other pipe has become
clogged. The generator should then be filled with
the required amount of water. In charging carbide
feed machines be careful not to place less than
a gallon of water in the water compartment for each
pound of carbide to be used and the water must be
brought to, but not above, the proper level as indi-
cated by the mark or the maker's instructions. The
generating chamber must be filled with the proper
amount of water before any attempt is made to place
the carbide in its holder. This rule must always be
followed. It is also necessary that all automatic water
seals and valves, as well as any other water tanks,
be filled with clean water at this time.

Never recharge with carbide without first cleaning
the generating chamber and completely refilling with
clean water. Never test the generator or piping for
leaks with any flame, and never apply flame to any

ACETYLENE GENERATORS 71

open pipe or at any point other than the torch, and
only to the torch after it has a welding or cutting
nozzle attached. Never use a lighted match, lamp,
candle, lantern, cigar or any open flame near a gen-
erator. Failure to observe these precautions is liable
to endanger life and property.

Operation and Care of Generators. — The following
instructions apply especially to the Davis Bournon-
ville pressure generator, illustrated in Figure 11.
The motor feed mechanism is illustrated in Figure 12.

Before filling the machine,, the cover should be
removed and the hopper taken out and examined to
see that the feeding disc revolves freely; that no
chains have been displaced or broken, and that the
carbide displacer itself hangs barely free^of the feed-
ing disc when it is revolved. After replacing the
cover, replace the bolts and tighten them equally, a
little at a time all around the circumference of the
cover — not screwing tight in one place only. Do not
screw the cover down any more than is necessary to
make a tight fit.

To charge the generator, proceed as follows : Open
the vent valve by turning the handle which extends
over the filling tube until it stands at a right angle
with the generator. Open the valve in the water
filling pipe, and through this fill with water until it
runs out of the overflow pipe of the drainage cham-
ber ; then close the valve in the water filling pipe and
vent valve. Remove the carbide filling plugs and fill
the hopper with li/4"x%" carbide ("nut" size).
Then replace the plugs and the safety-locking lever
chains. Now rewind the motor weight. Run the
pressure up to about five pounds by raising the con-
trolling diaphragm valve lever by hand (Figure 12,

72

WELDING

lever marked E). Then raise the blow-off lever,
allowing the gas to blow off until the gauge shows
about two pounds; this to clear the generator of air
mixture. Then run the pressure up to about eight

Figure 11. — Pressure Generator (Davis Bournonville). A, Feed
motor weight; B, Carbide feed motor; C, Motor control diaphragm;
D, Carbide hopper ; E, Carbide feed disc ; F, Overflow pipe ; G, Over-
flow pipe seal ; H, Overflow pipe valve ; J, Filling funnel ; K, Hydraulic
valve ; L, Expansion chamber ; M , Escape pipe ; N, Feed pipe ; O,
Agitator for residuum ; P3 Residuum valve ; Q, Water level

ACETYLENE GENERATORS 73

pounds by raising the controlling valve lever E, or
until this controlling lever rests against the upper
wing of the fan governor, and prevents operation
of the feed motor. After this is done, ,the motor will
operate automatically as the gas is consumed.

Should the pressure rise much above the blow-off
point, the safety controlling diaphragm valve will
operate and throw the safety clutch in interference

Figure 12. — Feed Mechanism of Pressure Generator

and thus stop the motor. This interference clutch
will then have to be returned to its former position
before the motor will operate, but cannot be replaced
before the pressure has been reduced below the blow-
off point.

The parts of the feed mechanism illustrated in
Figure 12 are as follows : A, motor drum for weight
cable. B, carbide filling plugs. C, chains for con-
necting safety locking lever of motor to pins on the-
top of the carbide plugs. D, interference clutch of
motor. E, lever on feed controlling diaphragm valve.

74 WELDING

F, lever of interference controlling diaphragm valve
that operates interference clutch. G, feed controlling
diaphragm valve. H, diaphragm valve controlling
operation of interference clutch. I, interference pin
to engage emergency clutch. J, main shaft driving
carbide feeding disc. Y, safety locking lever.

Recharging Generator. — Turn the agitator handle
rapidly for several revolutions, and then open the
residuum valve, having five or six pounds gas pres-
sure on the machine. If the carbide charge has been
exhausted and the motor has stopped, there is gen-
erally enough carbide remaining in the feeding disc
that can be shaken off, and fed by running the motor
to obtain some pressure in the generator. The desir-
ability of discharging the residuum with some gas
pressure is because the pressure facilitates the dis-
charge and at the same time keeps the generator full
of gas, preventing air mixture to a great extent. As
soon as the pressure is relieved by the withdrawal of
the residuum, the vent valve should be opened, as if
the pressure is maintained until all of the residuum
is discharged gas would escape through the discharge
valve.

Having opened the vent pipe valve and relieved
the pressure, open the valve in the water filling tube.
Close the residuum valve, then run in several gallons
of water and revolve the agitator, after which draw
out the remaining . residuum ; then again close the
residuum valve and pour in water until it discharges
from the overflow pipe of the drainage chamber. It
is desirable in filling the generator to pour the wTater
in rapidly enough to keep the filling pipe full of
water, so that air will not pass in at the same time.

After the generator is cleaned and filled with

ACETYLENE GENERATORS 75

water, fill with carbide and proceed in the same man-
ner as when first charging.

Carbide Feed Mechanism. — Any form of carbide
to water machine should be so designed that the car-
bide never falls directly from its - holder into the
water, but so that it must take a more or less cir-
cuitous path. This should be true, no matter what
position the mechanism is in. One of the commonest
types of forced feed machine carries the carbide in
a hopper with slanting sides, this hopper having a
large opening in the bottom through which the car-
bide passes to a revolving circular plate. As the
pieces of carbide work out toward the edge of the
plate under the influence of the mass behind them,
they are thrown off into the water by small stationary
fins or plows which are in such a position that they
catch the pieces nearest the edges and force them
off as the plate revolves. This arrangement, while
allowing a free passage for the carbide, prevents an
excess from falling should the machine stop in any
position.

When, as is usually the case, the feed mechanism
is actuated by the rise or fall of pressure in the
generator or of the level of some part of the gas
holder, it must be built in such a way that the feed-
ing remains inoperative as long as the filling opening
on the carbide holder remains open.

The feed of carbide should always be shut off and
controlled so that under no condition can more gas
be generated than could be cared for by the relief
valve provided. It is necessary also to have the feed
mechanism at least ten inches above the surface of
the water so that the parts will never become clogged
with damp lime dust.

76 WELDING

Motor Feed. — The feed mechanism itself is usually
operated by power secured from a slowly falling
weight which, through a cable, revolves a drum. To
this drum is attached suitable gearing for moving the
feed parts with sufficient power and in the way
desired. This part, called the motor, is controlled
by two levers, one releasing a brake and allowing the
motor to operate the feed, the other locking the gear-
ing so that no more carbide will be dropped into the
water. These levers are moved either by the quantity
of gas in the holder or by the pressure of the gas,
depending on the type of machine.

With a separate gas holder, such as used with low
pressure systems, the levers are operated by the rise
and fall of the bell of the holder or gasometer, alter-
nately starting and stopping the motor as the bell
falls and rises again. Medium pressure generators are
provided with a diaphragm to control the feed motor.

This diaphragm is carried so that the pressure
within the generator acts on one side while a spring,
whose tension is under the control of the operator,
acts on the other side. The diaphragm is connected
to the brake and locking device on the motor in
such a way that increasing the tension on the spring
presses the diaphragm and moves a rod that releases
the brake and starts the feed. The gas pressure,
increasing with the continuation of carbide feed, acts
on the other side and finally overcomes the pressure
of the spring tension, moving the control rod the
other way and stopping the motor and carbide feed.
This spring tension is adjusted and checked with the
help of a pressure gauge attached to the generating
chamber.

Gravity Feed. — This type of feed differs from the

ACETYLENE GENERATORS 77

foregoing in that the carbide is simply released and
is allowed to fall into the water without being forced
to do so. Any form of valve that is sufficiently
powerful in action to close with the carbide passing
through is used and is operated by the power secured
from the rise and fall of the gas holder bell. When
this valve is first opened the carbide runs into the
water until sufficient pressure and volume of gas is
generated to raise the bell. This movement operates
the arm attached to the carbide shut off valve and
slowly closes it. A fall of the bell occasioned by gas
being withdrawn again opens the valve and more gas
is generated.

Mechanical Feed. — The previously described meth-
ods of feeding carbide to the water have all been
automatic in action and do not depend on the oper-
ator for their proper action.

Some types of large generating plants have a
power-driven feed, the power usually being from
some kind of motor other than one operated by a
weight, such as a water motor, for instance This
motor is started and stopped by the operator when,
in his judgment, more gas is wanted or enough has
been generated. This type of machine, often called
a "non-automatic generator," is suitable for large
installations and is attached to a gas holder of suffi-
cient size to hold a day's supply of acetylene. The
generator can then be operated until a quantity of
gas has been made that will fill the large holder, or
gasometer, and then allowed to remain idle for some
time.

Gas Holders. — The commonest type of gas con-
tainer is that known as a gasometer. This consists
of a circular tank partly filled with water, into which

78 WELDING

is lowered another circular tank, inverted, which is
made enough smaller in 'diameter than the first one
so that three-quarters of an inch is left between them.
This upper and inverted portion, called the bell,
receives the gas from the generator and rises or falls
in the bath of water provided in the lower tank as
a greater or less amount of gas is contained in it.

These holders are made large enough so that they
will provide a means of caring for any after genera-
tion and so that they maintain a steady and even
flow. The generator, however, must be of a capacity
great enough so that the gas holder will not be drawn
on for part of the supply with all torches in opera-
tion. That is, the holder must not be depended on
for a reserve supply.

The bell of the holder is made so that when full
of gas its lower edge is still under a depth of at
least nine inches of water in the lower tank. Any
further rise beyond this point should always release
the gas, or at least part of it, to the escape pipe so
that the gas will under no circumstances be forced
into the room from between the bell and tank. The
bell is guided in its rise and fall by vertical rods so
that it will not wedge at any point in its travel.

A condensing chamber to receive the water which
condenses from the acetylene gas in the holder is
usually placed under this part and is provided with
a drain so that this water of condensation may be
easily removed.

Filtering. — A small chamber containing some
closely packed but porous material such as felt is
placed in the pipe leading to the torch lines. As
the acetylene gas passes through this filter the parti-
cles of lime dust and other impurities are extracted

ACETYLENE GENERATORS

79

from it so that danger of clogging the torch openings
is avoided a's much as possible.

The gas is also filtered to a large extent by its
passage through the water in the generating chamber,
this filtering or "scrubbing" often being facilitated
by the form of piping through which the gas must
pass from the generating chamber into the holder.
If the gas passes out of a number of small openings
when going into the holder the small bubbles give
a better washing than large ones would.

Piping. — Connections from generators to service
pipes should preferably be made with right and left
couplings or long thread nipples with lock nuts. If
unions are used, they should be of a type. that does
not require gaskets. The piping should be carried
and supported so that any moisture condensing in
the lines will drain back toward the generator and
where low points occur they should be drained
through tees leading into drip cups which are per-
manently closed with screw caps or plugs. No pet
cocks should be used for this purpose.

For the feed pipes to the torch lines the following
pipe sizes are recommended.
% inch pipe. 26 feet long.
3/2 inch pipe. 30 feet long.
% inch pipe. 50 feet long.

1 inch pipe. 70 feet long.
1% inch pipe. 100 feet long.
iy2 inch pipe. 150 feet long.

2 inch pipe. 200 feet long. 125 cubic feet per hour.
2y2 inch pipe. 300 feet long. 190 cubic feet per hour.

3 inch pipe. 450 feet long. 335 cubic feet per hour.
When drainage is possible into a sewer, the gen-
erator should not be connected directly into the sewer

2 cubic feet per hour.

4 cubic feet per hour.
15 cubic feet per hour.
27 cubic feet per hour.
50 cubic feet per hour.
65 cubic feet per hour.

80 WELDING

but should first discharge into an open receptacle,
which may in turn be connected to the sewer.

No valves or pet cocks should open into the gen-
erator room or any other room when it would be
possible, by opening them for draining purposes, to
allow any escape of gas. Any condensation must
be removed without the use of valves or other work-
ing parts, being drained into closed receptacles. It
should be needless to say that all the piping for gas
must be perfectly tight at every point in its length.

Safety Devices. — Good generators are built in such
a way that the operator must follow the proper order
of operation in charging and cleaning as well as in
all other necessary care. It has been mentioned that
the gas pressure is released or shut off before it is
possible to fill the water compartment, and this same
idea is carried further in making the generator inop-
erative and free from gas pressure before opening
the residue drain of the carbide filling opening on
top of the hopper. Some machines are made so that
they automatically cease to generate should there be
a sudden and abnormal withdrawal of gas such as
would be caused by a bad leak. This method of
adding safety by automatic means and interlocking
parts may be carried to any extent that seems desir-
able or necessary to the maker.

All 'generators should be provided with escape or
relief pipes of large size which lead to the open air.
These pipes are carried so that condensation will
drain back toward the generator and after being led
out of the building to a point at least twelve feet
above ground, they end in a protecting hood so that
no rain or solid matter can find its way into them.
Any escape of gas which might ordinarily pass into

ACETYLENE GENERATORS 81

the generator room is led into these escape pipes, all
parts of the system being connected with the pipe
so that the gas will find this way out.

Safety blow off valves are provided so that any
excess gas which cannot be contained by the gas
holder may be allowed to escape without causing an
undue rise in pressure. This valve also allows the
escape of pressure above that for which the generator
was designed. Gas released in this way passes into
the escape pipe just described.

Inasmuch as the pressure of the oxygen is much
greater than that of the acetylene when used in the
torch, it will be seen that anything that caused the
torch outlet to become closed would allow the oxygen
to force the acetylene back into the generator and
the oxygen would follow it, making a very explosive
mixture. This return of the gas is prevented by a
hydraulic safety valve or back pressure valve, as it is
often called.

Mechanical check valves have been found unsuit-
able for this use and those which employ water as a
seal are now required by the insurance rules. The
valve itself (Figure 13) consists of a large cylinder
containing water to a certain depth, which is indi-
cated on the valve body. Two pipes come into the
upper end of this cylinder and lead down into the
water, one being longer than the other. The shorter
pipe leads to the escape pipe mentioned above, while
the longer one comes from the generator. The upper
end of the cylinder has an opening to which is at-
tached the pipe leading to the torches.

The gas coming from the generator through the
longer pipe passes out of the lower end of the pipe
which is under water and bubbles up through the

WELDING

Figure 13. — Hydraulic B a c k-
Pressure Valve. A, Acetylene sup-
ply line; B, Vent pipe; C, Water
filling plug; D, Acetylene service
cock; E, Plug to gaa^e height of
water ; F, Gas openings under
water ; G, Return pipe for sealing
water ; H, Tube to carry gas be-
low water line ; /,, Tube to carry
gas to escape pipe ; J ' , Gas cham-
ber ; K, Plug in upper gas cham-
ber ; L, Hish water level ; M,
Opening through which water re-
turns ; O, Bottom clean out cast-
ing

ACETYLENE GENERATORS 83

water to the space in the top of the cylinder. From
there the gas goes to the pipe leading to the torches.
The shorter pipe is closed by the depth of water so
that the gas does not escape to the relief pipe. As
long as the gas flows in the normal direction as de-
scribed there will be no escape to the air. Should
the gas in the torch line return into the hydraulic
valve its pressure will lower the level of water in the
cylinder by forcing some of the liquid up into the
two pipes. As the level of the water lowers, the
shorter pipe will be uncovered first, and as this is
the pipe leading to the open air the gas will be
allowed to escape, while the pipe leading back to the
generator is still closed by the water seal. As soon
as this reverse flow ceases, the water will again resume
its level and the action will continue. Because of
the small amount of water blown out of the escape
pipe each time the valve is called upon to perform
this duty, it is necessary to see that the correct water
level is always maintained.

AVhile there are modifications of this construction,
the same principle is used in all types. The pressure
escape valve is often attached to this hydraulic valve
body.

Construction Details. — Flexible tubing (except at
torches), swring pipe joints, springs, mechanical check
valves, chains, pulleys and lead or fusible piping
should never be used on acetylene apparatus except
where the failure of those parts will not affect the
safety of the machine or permit, either directly or
indirectly, the escape of gas into a room. Floats
should not be used except where failure will only
render the machine inoperative.

It should be said that the National Board of Fire

84. WELDING

Underwriters have established an inspection service
for acetylene generators and any apparatus which
bears their label, stating that that particular model
and type has been passed, is safe to use. This service
is for the best interests of all concerned and looks
toward the prevention of accidents. Such inspection
is a very important and desirable feature of any
outfit and should be insisted upon.

Location of Generators. — Generators should pref-
erably be placed outside of insured buildings and
in properly constructed generator houses. The oper-
ating mechanism should have ample room to work
in and there should be room enough for the attendant
to reach the various parts and perform the required
duties without hindrance or the need of artificial
light. They should also be protected from tampering
by unauthorized persons.

Generator houses should not be within five feet of
any opening into, nor have any opening toward, any
adjacent building, and should be kept under lock and
key. The size of the house should be no greater than
called for by the requirements mentioned above and
it should be well ventilated.

The foundation for the generator itself should be
of brick, stone, concrete or iron, if possible. If of
wood, they should be extra heavy, located in a dry-
place and open to circulation of air. A board plat-
form is not satisfactory, but the foundation should
be of heavy planking or timber to make a firm base
and so that the air can circulate around the wood.

The generator should stand level and no strain
should be placed on any of the pipes or connections
or any parts of the generator proper.

CHAPTER IV

WELDING INSTRUMENTS

VALVES

Tank Valves. — The acetylene tank valve is of the
needle type, fitted with suitable stuffing box nuts and
ending1 in an exposed square shank to which the
special wrench may be fitted when the valve is to be
opened or closed.

The valve used on Linde oxygen cylinders is also
a needle type, but of slightly more complex construc-
tion. The body of the valve, which screws into the
top of the cylinder, has an opening below through
which the gas comes from the cylinder, and another
opening on the side through which it issues to the
torch line. A needle screws down from above to
close this lower opening. The needle which closes
the valve is not connected directly to the threaded
member, but fits loosely into it. The threaded part
is turned, by a small hand wheel attached to the upper
end. "When this hand wheel is turned to the left, or
up, as far as it will go, opening the valve, a rubber
disc is compressed inside of the valve body and this
disc serves to prevent leakage of the gas around the
spindle.

The oxygen valve also includes a safety nut having
a small hole through it closed by a fusible metal
which melts at 250° Fahrenheit. Melting of this
plug allows the gas to exert its pressure against a
thin copper diaphragm, this diaphragm bursting
under the gas pressure and allowing the oxygen to
escape into the air.

85

86

WELDING

The hand wheel and upper end of the valve mech-
anism are protected during shipment by a large steel
cap which covers them when screwed on to the end
of the cylinder. This cap should always be in place
when tanks are received from the makers or returned
to them.

>*IGH PRESSURE
GAUGE CON-

CONNECTION
TO OXYGEN CYLINOCR

Figure 14. — Regulating Valve

Regulating Valves. — While the pressure in the
gas containers may be anything from zero to 1,800
pounds, and will vary as the gas is withdrawn, the
pressure of the gas admitted to the torch must be
held steady and at a definite point. This is accom-
plished .by various forms of automatic regulating
valves, which, while they differ somewhat in details
of construction, all operate on the same principle.

The regulator body (Figure 14) carries a union
which attaches to the side outlet on the oxygen tank
valve. The gas passes through this union, following

WELDING INSTRUMENTS 87

an opening which leads to a large gauge which regis-
ters the pressure on the oxygen remaining in the tank
and also to a very small opening in the end of a tube.
The gas passes through this opening and into the
interior of the regulator body. Inside of the body
is a metal or rubber diaphragm placed so that the
pressure of the incoming gas causes it to bulge
slightly. Attached to the diaphragm is a sleeve or
an arm tipped writh a small piece of fibre, the fibre
being placed so that it is directly opposite the small
hole through which the gas entered the diaphragm
chamber. The slight movement of the diaphragm
draws the fibre tightly over the small opening through
which the gas is entering, with the result that further
flow is prevented.

Against the opposite side of the diaphragm is the
end of a plunger. This plunger is pressed against
the diaphragm by a coiled spring. The tension on
the coiled spring is controlled by the operator through
a threaded spindle ending in a wing or milled nut on
the outside of the regulator body. Screwing in on
the nut causes the tension on the spring to increase,
with a consequent increase of pressure on the side of
the diaphragm opposite to that on which the gas acts.
Inasmuch as the gas pressure acted to close the small
gas opening and the spring pressure acts in the oppo-
site direction from the gas, it will be seen that the
spring pressure tends to keep the valve open.

When the nut is turned way out there is, of course,
no pressure on the spring side of the diaphragm and
the first gas coming through automatically closes the
opening through which it entered. If now the ten-
sion on the spring be slightly increased, the valve
will again open and admit gas until the pressure of

88 WELDINa

gas within the regulator is just sufficient to overcome
the spring pressure and again close the opening.
There will then be a pressure of gas within the regu-
lator that corresponds to the pressure placed on the
spring by the operator. An opening leads from the
regulator interior to the torch lines so that all gas
going to the torches is drawn from the diaphragm
chamber.

Any withdrawal of gas will, of course, lower the
pressure of that remaining inside the regulator. The
spring tension, remaining at the point determined by
the operator, will overcome this lessened pressure of
the gas, and the valve will again open and admit
enough more gas to bring the pressure back to the
starting point. This action continues as long as the
spring tension remains at this point and as long as
any gas is taken from the regulator. Increasing the
spring tension will require a greater gas pressure to
close the valve and the pressure of that in the regu-
lator will be correspondingly higher.

When the regulator is not "being used, the hand
nut should be unscrewed until no tension remains on
the spring, thus closing the valve. After the oxygen
tank valve is open, the regulator hand nut is slowly
screwed in until the spring tension is sufficient to
give the required pressure in the torch lines. Another
gauge is attached to the regulator so that it com-
municates with the interior of the diaphragm cham-
ber, this gauge showing the gas pressure going to the
torch. It is customary to incorporate a safety valve
in the regulator which will blow off at a dangerous
pressure.

In regulating valves and tank valves, as well as
all other parts with which the oxygen comes in con-

WELDING INSTRUMENTS

89

tact, it is not permissible to use any form of oil or
grease because of danger of ignition and explosion.
The mechanism of a regulator is too delicate to be
handled in the ordinary shop and should any trouble
or leakage develop in this part of the equipment it
should be sent to a company familiar with this class
of work for the necessary repairs. Gas must never
be admitted to a regulator until the hand nut is all

Figure 15. — High and Low Pressure Gauges with Regulator

the way out, because of danger to the regulator itself
and to the operator as well. A regulator can only be
properly adjusted when the tank valve and torch
valves are fully opened.

Acetylene regulators are used in connection with
tanks of compressed gas. They are built on exactly
the same lines as the oxygen regulating valve and
operate in a similar way. One gauge only, the low
pressure indicator, is used for acetylene regulators,
although both high and low pressure may be used
if desired. (See Figure 15.)

90 WELDING

TORCHES

Flame is always produced by the combustion of
a gas with oxygen and in no other way. When we
burn oil or candles or anything else, the material of
the fuel is first turned to a gas by the heat and is
then burned by combining with the oxygen of the air.
If more than a normal supply of air is forced into
the flame, a greater heat and more active burning
follows. If the amount of air, and consequently oxy-
gen, is reduced, the flame becomes smaller and weaker
and the combustion is less rapid. A flame may be
easily extinguished by shutting off all of its air
supply.

The oxygen of the combustion only forms one-fifth
of the total volume of air; therefore, if we were to
supply pure oxygen in place of air, and in equal
volume, the action would be several times as intense.
If the oxygen is mixed with the fuel gas in the pro-
portion that burns to the very best advantage, the
flame is still further strengthened and still more heat
is developed because of the perfect combustion. The
greater the amount of fuel gas that can be burned
in a certain space and within a certain time, the
more heat will be developed from that fuel.'

The great amount of heat contained in acetylene
gas, greater than that found in any other gaseous
fuel, is used by leadfing this gas to the oxy-acetylene
torch and there combining it with just the right
amount of oxygen to make a flame of the greatest
power and heat than can possibly be produced by any
form of combustion of fuels of this kind. The heat
developed by the flame is about 6300° Fahrenheit and
easily melts all the metals, as well as other solids.

WELDING INSTRUMENTS 91

Other gases have been and are now being used in
the torch. None of them, however, produce the heat
that acetylene does, and therefore the oxy-acetylene
process has proved the most useful of all. Hydrogen
was used for many years before acetylene was intro-
duced in this field. The oxy-hydrogen flame develops
a heat far below that of oxy-acetylene, namely 4500'°
Fahrenheit. Coal gas, benzine gas, blaugas and
others have also been used in successful applications,
but for the present we will deal exclusively with the
acetylene fuel.

It was only with great difficulty that the obstacles
in the way of successfully using acetylene were over-
come by the development of practicable controlling
devices and torches, as well as generators. At pres.-
ent the oxy-acetylene process is the most universally
adaptable, and probably finds the most widely ex-
tended field of usefulness of any welding process.

The theoretical proportion of the gases for perfect
combustion is two and one-half volumes of oxygen to
one of acetylene. In practice this proportion is one
and one-eighth or one* and one-quarter volumes of
oxygen to one volume of acetylene, so that the cost
is considerably reduced below what it would be if the
theoretical quantity were really necessary, as oxygen
costs much more than acetylene in all cases.

While the heat is so intense as to fuse anything
brought into the path of the flame, it is localized in
the small "welding cone" at the torch tip so that
the torch is not at all difficult to handle without
special protection except for the eyes, as already
noted. The art of successful welding may be ac-
quired by any operator of average intelligence within
a reasonable time and with some practice. One

92 WELDING

trouble met with in the adoption of this process has
been that the operation looks so simple and so easy
of performance that unskilled and unprepared per-
sons have been tempted to try welding, with results
that often caused condemnation of the process, when
the real fault lay entirely with the operator.

The form of torch usually employed is from twelve
to twenty-four inches long and is composed of a
handle at one end with tubes leading from this handle
to the "welding head '^ or torch proper. At or near
one end of the handle are adjustable cocks or valves
for allowing the gases to flow into the tojrch or to
prevent them from doing so. These cocks are often
used for regulating the pressure and amount of gas
flowing to the welding head, but are not always con-
structed for this purpose and should not be so used
when it is possible to secure pressure adjustment at
the regulators (Figure 16).

Figure 16 shows three different sizes of torches.
The number 5 torch is designed especially for jew-
elers ' work and thin sheet steel welding. It is eleven
inches in length and weighs nineteen ounces. The
tips for the number 10 torch are interchangeable with
the number 5. The number 10 torch is adapted for
general use on light and medium heavy work. It
has six tips and its length is sixteen inches, with a
weight of twenty-three ounces.

The number 15 torch is designed for heavy work,
being twenty-five inches in length, permitting the
operator to stand away from the heat of the metal
being worked. These heavy tips are in two parts, the
oxygen check being renewable.

Figures 17 and 18 show two- sizes of another weld-
ing torch. Still another type is shown in Figure 19

WELDING INSTRUMENTS

93

g

(-*
O5

H
tr

!

94

WELDING

with four interchangeable tips, the function of each
being as fol]ows:

No. 1. For heavy castings.

No. 2. Light castings and heavy sheet metal.

No. 3. Light sheet metal.

No. 4. Very light sheet metal and wire.

4 3 3 t

Figure 17. — Cox Welding Torch (No. 1)

Figure 18. — Cox Welding Torch (No. 2)

Figure 19. — Monarch Welding Torch

At the side of the shut off cock away from the torch
handle the gas tubes end in standard forms of hose

WELDING INSTRUMENTS 95

nozzles, to which the rubber hose from the gas supply
tanks or generators can be attached. The tubes from
the handle to the head may be entirely separate from
each other, or one may be contained within the other.
As a general rule the upper one of two separate tubes
carries the oxygen, while this gas is carried in the
inside tube when they are concentric with each other.

In the welding head is the mixing chamber de-
signed to produce an intimate mixture of the two
gases before they issue from the nozzle to the flame.
The nozzle, or welding tip, of a suitable size and
design for the work to be handled and the pressure
of gases being used, is attached to the welding head,
and consists essentially of the passage at the outer
end of which the flame appears.

The torch body and tubes are usually made of
brass, although copper is sometimes used. The joints
must be very strong, and are usually threaded and
soldered with silver solder. The nozzle proper is
made from copper, because it withstands the heat
of the flame better than other less suitable metals.
The torch must be built in such a way that it is not
at all liable to come apart under the influence of
high temperatures.

All torches are constructed in such a way that it
is impossible for the gases to mix by any possible
chance before they reach the head, and the amount
of gas contained in the head and tip after being
mixed is made as small as possible. In order to
prevent the return of the flame through the acetylene
tube under the influence of the high pressure oxygen,
some form of back flash preventer is usually incor-
porated in the torch at or near the point at which
the acetylene enters. This preventer takes the form

96 WELDING

of some porous and heat absorbing material, such
as aluminum shavings, contained in a small cavity
through which the gas passes on its way to the head.
High Pressure Torches. — Torches are divided into
the same classes as are the generators; that is, high
pressure, medium pressure and low pressure. As
mentioned before, the medium pressure is usually
called the high pressure, because there are very few
true high pressure systems in use, and comparatively

Figure 20. — High Pressure Torch Head

speaking the medium pressure type is one of high
pressure.

With a true high pressure torch (Figure 20) the
gases are used at very nearly equal heads so that the
mixing before ignition is a simple matter. This type
admits the oxygen at the inner end of a straight
passage leading to the tip of the nozzle. The acety-
lene comes into this same passage from openings at
one side and near the inner end. The difference in
direction of the two gases as they enter the passage
assists in making a homogeneous mixture. The con-
struction of this nozzle is perfectly simple and is
easily understood. The true high pressure torch

WELDING INSTRUMENTS

97

nozzle is only suited for use with compressed and
dissolved acetylene, no other gas being at a sufficient
pressure to make the action necessary in mixing the
gases.

Medium Pressure Torches. — The medium pressure
(usually called high pressure) torch (Figure 21)
uses acetylene from a medium pressure generator
or from tanks of compressed gas, but will not take
the acetylene from low pressure generators.

Figure 21. — Medium Pressure Torch Head

The construction of the mixing chamber and nozzle
is very similar to that of the high pressure torch, the
gases entering in the same way and from the same
positions of openings. The pressure of the acetylene
is but little lower than that of the oxygen, and the
two gases, meeting at right angles, form a very inti-
mate mixture at this point of juncture. The mixture
in its proportions of gases depends entirely on the
sizes of the oxygen and acetylene openings into the
mixing chamber and on the pressures at which the
gases are admitted. There is a very slight injector
action as the fast moving stream of oxygen tends to
draw the acetylene from the side openings into the

98

WELDING

chamber, but the operation of the torch does not
depend on this action to any extent.

Low Pressure Torches. — The low pressure torch
(Figure 22) will use gas from low pressure gener-
ators, from medium pressure machines or from tanks
in which it has been compressed and dissolved. This
type depends for a perfect mixture of gas upon the
principle of the injector just as it is applied in steam
boiler practice.

Figure 22. — Low Pressure Torch with Separate Injector Nozzle

The oxygen enters the head at considerable pres-
sure and passes through its tube to a small jet within
the head. The opening of this jet is directly opposite
the end of the opening through the nozzle which
forms the mixing chamber and the path of the gases
to the flame. A small distance remains between the
opening from which the oxygen issues and the inner
opening into the mixing passage. The stream of
oxygen rushes across this space and enters the mixing
chamber, being driven by its own pressure.

The acetylene enters the head in an annular space
surrounding the oxygen tube. The space between
oxygen jet and mixing chamber opening is at one

WELDING INSTRUMENTS 99

end of this acetylene space and the stream of oxygen
seizes the acetylene and under the injector action
draws it into the mixing chamber, it being necessary
only to have a sufficient supply of acetylene flowing
into the head to allow the oxygen to draw the re-
quired proportion for a proper mixture.

The volume of gas drawn into the mixing chamber
depends on the size of the injector openings and the
pressure of the oxygen. In practice the oxygen
pressure is not altered to produce different sized
flames, but a new nozzle is substituted which is
designed to give the required flame. Each nozzle
carries its own injector, so that the design is always
suited to the conditions. While torches are made
having the injector as a permanent part of the torch
body, the replaceable nozzle is more commonly used,
because it makes the one torch suitable for a large
range of work and a large number of different sized
flames. "With the replaceable head a definite pressure
of oxygen is required for the size being used, this
pressure being the one for which the injector and
corresponding mixing chamber were designed in pro-
ducing the correct mixture.

Adjustable Injectors. — Another form of low pres-
sure torch operates on the injector principle, but the
injector itself is a permanent part of the torch, the
nozzle only being changed for different sizes of work
and flame. The injector is placed in or near the
handle and its opening is the largest required by any
work that can be handled by this particular torch.
The opening through the tip of the injector through
which the oxygen issues on its way to the mixing
chamber may be wholly or partly closed by a needle
valve which may be screwed into the opening or

100 WELDING

withdrawn from it, according to the operator's judg-
ment. The needle valve ends in a milled nut outside
the torch handle, this being the adjustment provided
for the different nozzles.

Torch Construction. — A well designed torch is so
designed that the weight distribution is best for hold-
ing it in the proper position for welding. When a
torch is grasped by its handle with the gas hose
attached, it should balance so that it does not feel
appreciably heavier on one end than on the other.

The head and nozzle may be placed so that the
flame issues in a line at right angles with the torch
body, or they may be attached at an angle convenient
for the work to be done. The head set at an angle
of from 120 to 170 degrees with the body is usually
preferred for general work in welding, while the
cutting torch usually has its head at right angles
to the body.

Removable nozzles have various size openings
through them and the different sizes are designated
by numbers from 1 up. The same number does not
always indicate the same size opening in torches of
different makes, nor does it indicate a nozzle of the
same capacity.

The design of the nozzle, the mixing chamber, the
injector, when one is used, and the size of the gas
openings must be such that all these things are suited
to each other if a proper mixture of gas is to be
secured. Parts that are not made to work together
are unsafe if used because of the danger of a flash
back of the flame into the mixing chamber and gas
tubes. It is well known that flame travels through
any inflammable gas at a certain definite rate of
speed, depending on the degree of inflammability of

WELDING INSTRUMJEjS^g? \J >>, \ ] A 101

the gas. The easier and quicker the gas burns, the
faster will the flame travel through it.

If the gas in the nozzle and mixing chamber stood
still, the flame would immediately travel back into
these parts and produce an explosion of more or less
violence. The speed with which the gases issue from
the nozzle prevent this from happening because the
flame travels back through the gas at the same speed
at which the gas issues from the torch tip. Should
the velocity of the gas be greater than the speed of
flame propagation through it, it will be impossible
to keep the flame at the tip, the tendency being for
a space of unburned gas to appear between tip and
flame. On the other hand, should the speed of the
flame exceed the velocity with which the gas comes
from the torch there will result a flash back and
explosion.

Care of Torches. — An oxy-acetylene torch is a very
delicate and sensitive device, much more so than
appears on the surface. It must be given equally
as good care and attention as any other high-priced
piece of machinery if it is to be maintained in good
condition for use.

It requires cleaning of the nozzles at regular inter-
vals if used regularly. This cleaning is accomplished
with a piece of copper or brass wire run through the
opening, and never with any metal such as steel or,
iron that is harder than the nozzle itself, because of
the danger of changing the size of the openings. -The
torch head and nozzle can often be cleaned by allow-
ing the oxygen to blow through at high pressure
without the use of any tools.

In using a torch a deposit of carbon will gradually
form inside of the head, and this deposit will be more

102 *' c * < WELDING

rapid if the operator lights the stream of acetylene
before turning any oxygen into the torch. This
deposit may be removed by running kerosene through
the nozzle while it is removed from the torch, setting
fire to the kerosene and allowing oxygen to flow
through while the oil is burning.

Should a torch become clogged in the head or
tubes, it may usually be cleaned by removing the
oxygen hose from the handle end, closing the acety-
lene cock on the torch, placing the end of the oxygen
hose over the opening in the nozzle and turning on
the oxygen under pressure to blow the obstruction
back through the passage that it has entered. By
opening the acetylene cock and closing the oxygen
cock at the handle, the acetylene passages may then
be cleaned in the same way. Under no conditions'
should a torch be taken apart any more than to
remove the changeable nozzle, except in the hands of
those experienced in this work.

Nozzle Sizes. — The size of opening through the
nozzle is determined according to the thickness and
kind of metal being handled. The following sizes
are recommended for steel :

Davis-Bournonville. O x w e 1 d Low

Thickness of Metal (Medium Pressure.) Pressure

1/32 Tip No. 1 Head No. 2

1/16 2

5/64 3

3/32 3 4

1/8 4 5

3/16 5 6

1/4 6 7

5/16 7

3/8 8 8

1/2 9 10

5/8 10 12

3/4 11 15

Very heavy 12 15

WELDING INSTRUMENTS 103

Cutting Torches. — Steel may be cut with a jet of
oxygen at a rate of speed greater than in any other
practicable way under usual conditions. The action
consists of burning away a thin section of the metal
by allowing a stream of oxygen to flow onto it while
the gas is at high pressure and the metal at a white
heat.

The cutting torch (Figure 23) has the same char-
acteristics as the welding torch, but has an additional
nozzle or means for temporarily using the welding

Figure 23. — Cutting Torch

opening for the high pressure oxygen. The oxygen
issues from the opening while cutting at a pressure
of from ten to 100 pounds to the square inch.

The work is first heated to a white heat by adjust-
ing the torch for a welding flame. As soon as the
metal reaches this temperature, the high pressure
oxygen is turned on to the white-hot portion of the
steel. When the jet of gas strikes the metal it cuts
straight through, leaving a very narrow slot and
removing but little metal. Thicknesses of steel up
to ten inches can be economically handled in this
way.

The oxygen nozzle is usually arranged so that it
is surrounded by a number of small jets for the
heating flame. It will be seen that this arrangement

104 WELDING

makes the heating flame always precede the oxygen
jet, no matter in which direction the torch is moved.

The torch is held firmly, either by hand or with
the help of special mechanism for guiding it in the
desired path, and is steadily advanced in the direc-
tion it is desired to extend the cut, the rate of
advance being from three inches to two feet per
minute through metal from nine inches down to one-
quarter of an inch in thickness.

The following data on cutting is given by the
Davis-Bournonville Company :

•3 5 |

2 a * $$ *

S -8 2s & s

° 5 * °* ft ?s

O O ~° * - 00

j s I !! A » *

II I !i I! I !l

1/4 lOlbs. 41bs. .40 .086 24 $ .013

1/2 20 4 .91 .150 15 .029

3/4 30 4 1.16 .150 15 .036

1 30 4 1.45 .172 12 .045
11/2 30 5 2.40 .380 12 .076

2 40 5 2.96 .380 12 .093
4 50 5 9.70 .800 7 .299
6 70 6 21.09 1.50 4 .648
9 100 6 43.20 2.00 3 1.311

Acetylene-Air Torch. — A form of torch which
burns the acetylene after mixing it with atmospheric
air at normal pressure rather than with the oxygen
under higher pressures has been found useful in
certain pre-heating, brazing and similar operations.
This torch (Figure 24) is attached by a rubber gas
hose to any compressed acetylene tank and is regu-
lated as to flame size and temperature by opening or
closing the tank valve more or less.

WELDING INSTRUMENTS 105

After attaching the torch to the tank, the gas is
turned on very slowly and is lighted at the torch tip.
The adjustment should cause the presence of a green-
ish-white cone of flame surrounded by a larger body
of burning gas, the cone starting at the mouth of
the torch.

By opening the tank valve more, a longer and
hotter flame is produced, the length being regulated

Figure 24. — Acetylene-Air Torch

.

by the tank valve also. This torch will give sufficient
heat to melt steel, although not under conditions
suited to welding. Because of the excess of acetylene
always present there is no danger of oxidizing the
metal being heated.

The only care required by this torch is to keep the
small air passages at the nozzle clean and free from
carbon deposits. The flame should be extinguished
when not in use rather than turned low, because this
low flame rapidly deposits large quantities of soot
in the burner.

CHAPTER V

OXY-ACETYLENE WELDING PEACTICE
PREPARATION OF WORK

Preheating. — The practice of heating the metal
around the weld before applying the torch flame is
a desirable one for two reasons. First, it makes the
whole process more economical; second, it avoids the
danger of breakage through expansion and contrac-
tion of the work as it is heated and as it cools.

When it is desired to join two surfaces by welding
them, it is, of course, necessary to raise the metal
from the temperature of the surrounding air to its
melting point, involving an increase in temperature
of from one thousand to nearly three thousand de-'
grees. To obtain this entire increase of temperature
with the torch flame is very wasteful of fuel and of
the operator's time. The total amount of heat nec-
essary to put into metal is increased by the con-
ductivity of that metal because the heat applied at
the weld is carried to other parts of the piece being
handled until the whole mass is considerably raised
in temperature. To secure this widely distributed
increase the various methods of preheating are
adopted.

As to the second reason for preliminary heating.
It is understood that the metal added to the joint is
molten at the time it flows into place. All the metals
used in welding contract as they cool and occupy
a much smaller space than when molten. If addi-
tional metal is run between two adjoining surfaces
which are parts of a surrounding body of cool metal,

106

OXY-ACETYLENE WELDING PRACTICE 107

this added metal will cool while the surfaces them-
selves are held stationary in the position they Grig-*
in ally occupied. The inevitable result is that the
metal added will crack under the strain, or, if the
weld is exceptionally strong, the main body of the
work will be broken by the force of contraction. To
overcome these difficulties is the second and most
important reason for preheating and also for slow
cooling following the completion of the weld.

There are many ways of securing this preheating.
The work may be brought to a red heat in the forge
if it is cast iron or steel ; it may be heated in special
ovens built for the purpose; it may be placed in a
bed of charcoal while . suitably supported; it may be
heated by gas or gasoline preheating torches, and
with very small Work the outer flame of the welding
torch automatically provides means to this end.

The temperature of the parts heated should be
gradually raised in all cases, giving the entire mass
of metal a chance to expand equally arid to adjust
itself to the strains imposed by the preheating. After
the region around the weld has been brought to a
proper temperature the opening to be filled is ex-
posed so that the torch flame can reach it, while the
remaining surfaces are still protected from cold air
currents and from cooling through natural radiation.

One of the commonest methods and one of the best
for handling work of rather large size is to place the
piece to be welded on a bed of fire brick and build
a loose wall around it with other fire brick placed in
rows, one on top of the other, with air spaces left
between adjacent bricks in each row. The space
between the brick retaining wall and the work is
filled with charcoal, which is lighted . from below.

108

The top opening of the temporary oven is then cov-
ered with asbestos and the fire kept up until the
work has been uniformly raised in temperature to
the desired point.

When much work of the same general character
and size is to be handled, a permanent oven may be
constructed of fire brick, leaving a large opening
through the top and also through one side. Charcoal
may be used in this form of oven as with the tem-
porary arrangement, or the heat may be secured
from any form of burner or torch giving a large
volume of flame. In any method employing flame to
do the heating, the work itself must be protected
from the direct blast of the fire. Baffles of brick or
metal should be placed between the mouth of the
torch and the nearest surface of the work so that
the flame will be deflected to either side and around
the piece being heated.

The heat should be applied to bring the point of
welding to the highest temperature desired and, ex-
cept in the smallest work, the heat should gradually
shade off from this point to the other parts of the
piece. In the case of cast iron and steel the tem-
perature at the point to be welded should be great
enough to produce a dull red heat. This will make
the whole operation much easier, because there will
be no surrounding cool metal to reduce the tempera-
ture of the molten material from the welding rod
below the point at which it will join the work. From
this red heat the mass of metal should grow cooler
as the distance from the weld becomes greater, so
that no great strain is placed upon any one part.
With work of a very irregular shape it is always
best to heat the entire piece so that the strains will

OXY-ACETYLENE WELDING PRACTICE 109

be so evenly distributed that they can cause no dis-
tortion or breakage under any conditions.

The melting point of the work which is being pre-
heated should be kept in mind and care exercised not
to approach it too closely. Special care is necessary
with aluminum in this respect, because of its low
melting temperature and the sudden weakening and
flowing without warning. Workmen have carelessly
overheated aluminum castings and, upon uncovering
the piece to make the weld, have been astonished to
find that it had disappeared. Six hundred degrees
is about the safe limit for this metal. It is possible
to gauge the exact temperature of the work with a
pyrometer, but when this instrument cannot be pro-
cured, it might be well to secure a number of "tem-
perature cones" from a chemical or laboratory sup-
ply house. These cones are made from material that
will soften at a certain heat and in form they are
long and pointed. Placed in position on the part
being heated, the point may be watched, and when
it bends over it is sure that the metal itself has
reached a temperature considerably in excess of the
temperature at which that particular cone was de-
signed to soften.

The object in preheating the metal around the
weld is to cause it to expand sufficiently to open the
crack a distance equal to the contraction when cool-
ing from the melting point. In the case of a crack
running from the edge of a piece into the body or
of a crack wholly within the body, it is usually satis-
factory to heat the metal at each end of the opening.
This will cause the whole length of the crack to open
sufficiently to receive the molten material from the
rod.

110

WELDING

The judgment of the operator will be called upon
to decide just where a piece of metal should be heated
to open the weld properly. It is often possible to
apply the preheating flame to a point some distance
from the point of work if the parts are so connected

^gS^s^^S

I^S^i

gi^^;sgs$^^!^^^^^^

•ggsaa^y^sscassissss

s^s^Sd

Figure 25. — Preheating at A While Welding at B. C also May Be
Heated

that the expansion of the heated part will serve to
draw the edges of the weld apart. Whatever part
of the work is heated to cause expansion and separa-
tion, this part must remain hot during the entire
time of welding and must then cool slowly at the
same time as the metal in the weld cools.

An example of heating points away from the crack
might be found in welding a lattice work with one

OXY-ACETYLENE WELDING PRACTICE 111

of the bars cracked through (Figure 25). If the
strips parallel and near to the broken bar are heated
gradually, the work will be so expanded that the
edges of the break are drawn apart and the weld
can be successfully made. In this case, the parallel
bars next to the broken one would be heated highest,
the next row not quite so hot and so on for some
distance away. If only the one row were heated, the

Figure 26. — Cutting Through the Rim of a Wheel (Cut Shown at A)

strains set up in the next ones would be sufficient
to cause a new break to appear.

If welding is to be done near the central portion
of a large piece, the strains will be brought to bear
on the parts farthest away from the center. Should
a fly wheel spoke be broken and made ready to weld,
the greatest strain will come on the rim of the wheel.
In cases like this it is often desirable to cut through
at the point of greatest strain with a saw or cutting
torch, allowing free movement while the weld is
made at the original break (Figure 26). After the

112 WELDING

inside weld is completed, the cut may be welded
without danger, for the reason that it will always
be at some point at which severe strains cannot be
set up by the contraction of the cooling metal.

In materials that will spring to some extent with-
out breakage, that is, in parts that are not brittle, it
may be possible to force the work out of shape with
jacks or wedges (Figure 27) in the same way that
it would be distorted by heating and expanding some
portion of it as described. A careful examination
will show whether this method can be followed in
such a way as to force the edges of the break to

Figure 27. — Using a Wedge While Welding

separate. If the plan seems feasible, the wedges
may be put in place and allowed to remain while the
weld is completed. As soon as the work is finished
the wedges should be removed so that the natural
contraction can take place without damage.

It should always be remembered that it is not so
much the expansion of the work when heated as it
is the contraction caused by cooling that will do the
damage. A weld may be made that, to all appear-
ances, is perfect and it may be perfect when com-
pleted; but if provision has not been made to allow
for the contraction that is certain to follow, there
will be a breakage at some point. It is not possible
to weld the simplest shapes, other than straight bars,
without considering this difficulty and making pro-
vision to take care of it.

OXY-ACETYLENE WELDING PRACTICE 113

The exact method to employ in preheating will
always call for good judgment on the part of the
workman, and he should remember that the success
or failure of his work will depend fully as much on
proper preparation as on correct handling of the
wreld itself. It should be remembered that the outer
flame of the oxy-acetylene torch may be depended
on for a certain amount of preheating, as this flame
gives a very large volume of heat, but a heat that
is not so intense nor so localized as the welding flame
itself. The heat of this part of the flame should be
fully utilized during the operation of melting the
metal and it should be so directed, when possible,
that it will bring the parts next to be joined to as
high a temperature as possible.

When the work has been brought to the desired
temperature, all parts except the break and the sur-
face immediately surrounding it on both sides should
be covered with heavy sheet asbestos. This protect-
ing cover should remain in place throughout the
operation and should only be moved a distance suffi-
cient to allow the torch flame to travel in the path
of the weld. The use of asbestos in this way serves
a twofold purpose. It retains the heat in the work
and prevents the breakage that would follow if a
draught of air were to strike the heated metal,
and it also prevents such a radiation of heat through
the surrounding air as would make it almost impos-
sible for the operator to perform his work, especially
in the case of large and heavy castings when the
amount of heat utilized is large.

Cleaning and, Champ fering. — A perfect weld can
never be made unless the surfaces to be joined have
been properly prepared to receive the new metal.

114 WELDING

All spoiled, burned, corroded and rough particles
must positively be removed with .chisel and hammer
and with a free application of emery cloth and wire
brush. The metal exposed to the welding flame
should be perfectly clean and bright all over, or
else the additional material will not unite, but will
only stick at best.

Following the cleaning it is always necessary to
bevel, or champfer, the edges except in the thinnest

Figure 28. — Tapering the Opening Formed by a Break

sheet metal. To make a weld that will hold, the
metal must be made into one piece, without holes or
unfilled portions at any point, and must be solid
from inside to outside. This can only be accom-
plished by starting the addition of metal at one
point and gradually building it up until the outside,
or top, is reached. With comparatively thin plates
the molten metal may be started from the side far-
thest from the operator and brought through, but
with thicker sections the addition is started in the
middle and brought flush with one side and then
with the other.

It will readily be seen that the molten material

OXY-ACETYLENE WELDING PRACTICE 115

cannot be depended upon to flow between the tightly
closed surfaces of a crack in a way that can be at all
sure to make a true weld. It will be necessary for
the operator to reach to the farthest side with the
flame and welding rod, and to start the new surfaces
there. To allow this, the edges that are to be joined
are beveled from one side to the other (Figure 28),
so that when placed together in approximately the
position they are to occupy they will leave a grooved
channel between them with its sides at an angle with

\

Figure 29. — Beveling for Thin Work

Figure 30. — Beveling for Thick Work

each other sufficient in size to allow access to every
point of each surface.

With work less than one-fourth inch thick, this
angle should be forty-five degrees on each piece
(Figure 29), so that when they are placed together
the extreme edges will meet at the bottom of a
groove whose sides are square, or at right angles,
to each other. This beveling should be done so that
only a thin edge is left where the two parts come
together, just enough points in contact to make the
alignment easy to hold. With work of a thickness
greater than a quarter of an inch, the angle of bevel
on each piece may be sixty degrees (Figure 30), so
that when placed together the angle included be-

116

WELDING

tween the sloping sides will also be sixty degrees.
If the plate is less than one-eighth of an inch thick
the beveling is not necessary, as the edges may be
melted all the way through without danger of leaving
blowholes at any point.

This beveling may be done in any convenient way.
A chisel is usually most satisfactory and also quick-
est. Small sections may be handled by filing, while
metal that is too hard to cut in either of these wavs

Figure 31. — Beveling Both Sides of a Thick Piece

Figure 32. — Beveling the End of a Pipe

may be shaped on the emery wheel. It is not nec-
essary that the edges be perfectly finished and abso-
lutely smooth, but they should be of regular outline
and should always taper off to a thin edge so that
when the flame is first applied it can be seen issuing
from the far side of the crack. If the work is quite
thick and is of a shape that will allow it to be turned
over, the bevel may be brought from both sides
(Figure 31), so that there will be two grooves, one
on each surface of the work. After completing the
weld on one side, the piece is reversed and finished
on the other side. Figure 32 shows the proper bevel-

OXY-ACETYLENE WELDING PRACTICE 117

ing for welding pipe. Figure 33 shows how sheet
metal may be flanged for welding.

Welding should not be attempted with the edges
separated in place of beveled, because it will be
found impossible to build up a solid web of new
metal from one side clear through to the other by
this method. The flame cannot reach the surfaces
to make them molten while receiving new material
from the rod, and if the flame does not reach them
it will only serve to cause a few drops of the metal
to join and will surely cause a weak and defective
weld.

, nn _,

i JV__

Figure 33. — Flanging Sheet Metal for Welding

Supporting Work. — During the operation of weld-
ing it is necessary that the work be well supported
in the position it should occupy. This may be done
with fire brick placed under the pieces in the correct
position, or, better still, with some form of clamp.
The edges of the crack should touch each other at
the point where welding is to start and from there
should gradually separate at the rate of about one-
fourth inch to the foot. This is done so that the
cooling of the molten metal as it is added will draw
the edges together by its contraction.

Care must be used to see that the work is sup-
ported so that it will maintain the same relative
position between the parts as must be present when
the work is finished. In this connection it must be

118

WELDING

remembered that the expansion of the metal when
heated may be great enough to cause serious dis-
tortion and to provide against this is one of the
difficulties to be overcome.

Perfect alignment should be secured between the
separate parts that are to be joined and the two
edges must be held up so that they will be in the
same plane while welding is carried out. If, by any
chance, one drops below the other while molten metal

Figure 34. — Rotary Movement of Torch in Welding

is being added, the whole job may have to be undone
and done over again. One precaution that is nec-
essary is that of making sure that the clamping or
supporting does not in itself pull the work out of
shape while melted.

TORCH PRACTICE

The weld is made by bringing the tip of the weld-
ing flame to the edges of the metals to be. joined.
The torch should be held in the right hand and
moved slowly along the crack with a rotating motion,
traveling in small circles (Figure 34), so that the

OXY-ACETYLENE WELDING PRACTICE 119

welding flame touches first on one side of the crack
and then on the other. On large work the motion
may be simply back and forth across the crack,
advancing regularly as the metal unites. It is
usually best to weld toward the operator rather than
from him, although this rule is governed by circum-
stances. The head of the torch should be inclined
at an angle of about %60 degrees to the surface of the
work. The torch handle should extend in the same
line with the break (Figure 35) and not across it,
except when welding very light plates.

Figure 35. — Torch Held in Line with the Break

If the metal is 1/16 inch or less in thickness it is
only necessary to circle along the crack, the metal
itself furnishing enough material to complete the
weld without additions. Heat both sides evenly until
they flow together.

Material thicker than the above requires the addi-
tion of more metal of the same or different kind from
the welding rod, this rod being held by the left hand.
The proper size rod for cast iron is one having a
diameter equal to the thickness of metal being welded
up to a one-half inch rod, which is the largest used.
For steel the rod should be one-half the thickness
of the metal being joined up to one-fourth inch rod.

120

WELDING

As a general rule, better results will be obtained
by the use of smaller rods, the very small sizes being
twisted together to furnish enough material while
retaining the free melting qualities.

The tip of the rod must at all times be held in
contact with the pieces being welded and the flame

Figure 36. — The Welding Rod Should Be Held in the Molten Metal

must be so directed that the two sides of the crack
and the end of the rod are melted at the same time
(Figure 36). Before anything is added from the
rod, the sides of the crack are melted down suffi-
ciently to fill the bottom of the groove and join the

Figure 37. — Welding Pieces of Unequal Thickness

two sides. Afterward, as metal comes from the rod
in filling the crack, the flame is circled along the
joint being made, the rod always following the
flame.

Figure 37 illustrates the welding of pieces of
unequal thickness.

OXY-ACETYLENE WELDING PRACTICE 121

Figure 38 illustrates welding at an angle.

The molten metal may be directed as to where it
should go by the tip of the welding flame, which has
considerable force, but care must be taken not to
blow melted metal on to cooler surfaces which it
cannot join. If, while welding, a spot appears which
does not unite with the weld, it may be handled by
heating all around it to a white heat and then imme-
diately welding the bad place.

J

Figure 38. — Welding at an Angle

Never stop in the middle of a weld, as it is ex-
tremely difficult to continue smoothly when resuming
work.

The Flame. — The welding flame must have exactly
the right proportions of each gas. If there is too
much oxygen, the metal will be burned or oxidized;
the presence of too much acetylene carbonizes the
metal; that is to say, it adds carbon and makes the
work harder. Just the right mixture will neither
burn nor carbonize and is said to be a "neutral"
flame. The neutral flame, if of the correct size for
the work, reduces the metal to a melted condition,
not too fluid, and for a width about the same as the
thickness of the metal being welded.

"When ready to light the torch, after attaching the

122 WELDING

right tip or head as directed in accordance with the
thickness of metal to be handled, it will be necessary
to regulate the pressure of gases to secure the neutral
flame.

The oxygen will have a pressure of from 2 to 20
pounds, according to the nozzle used. The acetylene
will have much less. Even with the compressed gas,
the pressure should never exceed 10 pounds for the
largest work, and it will usually be from 4 to 6.
In low pressure systems, the acetylene will be re-
ceived at generator pressure. It should first be seen
that the hand-screws on the regulators are turned
way out so that the springs are free from any ten-
sion. It will do no harm if these screws are turned
back until they come out of the threads. This must
be done with both oxygen and acetylene regulators.

Next, open the valve from the generator, or on
the acetylene tank, and carefully note whether there
is any odor of escaping gas. Any leakage of this
gas must be stopped before going on with the work.

The hand wheel controlling the oxygen cylinder
valve should now be turned very slowly to the left
as far as it will go, which opens the valve, and it
should be borne in mind the pressure that is being
released. Turn in the hand screw on the oxygen
regulator until the small pressure gauge shows a
reading according to the requirements of the noz-
zle being used. This oxygen regulator adjustment
should be made with the cock on the torch open,
and after the regulator is thus adjusted the torch
cock may be closed.

Open the acetylene cock on the torch and screw
in on the acetylene regulator hand-screw until gas
commences to come through the torch. Light this

OXY-ACETYLENE WELDING PRACTICE 123

flow of acetylene and adjust the regulator screw to
the pressure desired, or, if there is no gauge, so that
there is a good full flame. With the pressure of
acetylene controlled by the type of generator it will
only be necessary to open the torch cock.

With the acetylene burning, slowly open the oxy-
gen cock on the torch and allow this gas to join the
flame. The flame will turn intensely bright and then
blue white. There will be an outer flame from four
to eight inches long and from one to three inches
thick. Inside of this flame will be two more rather
distinctly defined flames. The inner one at the torch
tip is very small, and the intermediate one is long
and pointed. The oxygen should be turned on until
the two inner flames unite into one blue-white cone
from one-fourth to one-half inch long and one-eighth
to one-fourth inch in diameter. If this single, clearly
defined cone does not appear when the oxygen torch
cock has been fully opened, turn off some of the
acetylene until it does appear.

If too much oxygen is added to the flame, there
will still be the central blue-white cone, but it will
be smaller and more or less ragged around the edges
(Figure 39). When there is just enough oxygen to
make the single cone, and when, by turning on more
acetylene or by turning off oxygen, two cones are
caused to appear, the flame is neutral (Figure 40),
and the small blue-white cone is called the welding
flame.

While welding, test the correctness of the flame
adjustment occasionally by turning on more acety-
lene or by turning off some oxygen until two flames
or cones appear. Then regulate as before to secure
the single distinct cone. Too much oxygen is not

124 WELDING

usually so harmful as too much acetylene, except
with aluminum. (See Figure 41.) An excessive
amount of sparks coming from the weld denotes that

Figure 39. — Oxidizing Flame — Too Much Oxygen

Figure 40. — Neutral Flame

Figure 41. — Reducing Flame — Showing an Excess of Acetylene

OXY-ACETYLENE WELDING PRACTICE 125

there is too much oxygen in the flame. Should the
opening in the tip become partly clogged, it will be
difficult to secure a neutral flame and the tip should
be cleaned with a brass or copper wire — never with
iron or steel tools or wire of any kind. While the
torch is doing its work, the tip may become exces-
sively hot due to the heat radiated from the molten
metal. The tip may be cooled by turning off the
acetylene and dipping in water with a slight flow
of oxygen through the nozzle to prevent water find-
ing its way into the mixing chamber.

The regulators for cutting are similar to those for
welding, except that higher pressures may be han-
dled, and they are fitted with gauges reading up to
200 or 250 pounds pressure.

In welding metals which conduct the heat very
rapidly it is necessary to use a much larger nozzle
and flame than for metals which have not this prop-
erty. This peculiarity is found to the greatest extent
in copper, aluminum and brass.

Should a hole be blown through the work, it may
be closed by withdrawing the flame for a few sec-
onds and then commencing to build additional metal
around the edges, working all the way around and
finally closing the small opening left at the center
with a drop or two from the welding rod.

WELDING VARIOUS METALS

Because of the varying melting points, rates of
expansion and contraction, and other peculiarities
of different metals, it is necessary to give detailed
consideration to the most important ones.

Characteristics of Metals. — The welder should thor-
oughly understand the peculiarities of the various

126 WELDING

metals with which he has to deal. The metals and
their alloys are described under this heading in the
first chapter of this book and a tabulated list of the
most important points relating to each metal will
be found at the end of the present chapter. All this
information should be noted by the operator of a
welding installation before commencing actual work.

Because of the nature of welding, the melting
point of a metal is of great importance. A metal
melting at a low temperature should have more care-
ful treatment to avoid undesired flow than one which
melts at a temperature which is relatively high.
When two dissimilar metals are to be joined, the
one which melts at the higher temperature must be
acted upon by the flame first and when it is in a
molten condition the heat contained in it will in
many cases be sufficient to cause fusion of the lower
melting metal and allow them to unite without play-
ing the flame on the lower metal to any great extent.

The heat conductivity bears a very important
relation to welding, inasmuch as a metal with a high
rate of conductance requires more protection from
cooling air currents and heat radiation than one not
having this quality to such a marked extent. A
metal which conducts heat rapidly will require a
larger volume of flame, a larger nozzle, than other-
wise, this being necessary to supply the additional
heat taken away from the welding point by this
conductance.

The relative rates of expansion of the various
metals under heat should be understood in order that
parts made from such material may have proper*
preparation to compensate for this expansion and
contraction. Parts made from metals having widely

OXY-ACETYLENE WELDING PRACTICE 127

varying rates of expansion must have special treat-
ment to allow for this quality, otherwise breakage
is sure to occur.

Cast Iron. — All spoiled metal should be cut away
and if the work is more than one-eighth inch in
thickness the sides of the crack should be beveled
to a 45 degree angle, leaving a number of points
touching at the bottom of the bevel so that the work
may be joined in its original relation.

The entire piece should be preheated in a bricked-up
oven or with charcoal placed on the forge, when size
does not warrant building a temporary oven. The
entire piece should be slowly heated and the portion
immediately surrounding the weld should be brought
to a dull red. Care should be used that the heat does
not warp the metal through application to one part
more than the others. After welding, the work
should be slowly cooled by covering with ashes,
slaked lime, asbestos fibre or some other non-con-
ductor of heat. These precautions are absolutely
essential in the case of cast iron.

A neutral flame, from a nozzle proportioned to the
thickness of the work, should be held with the point
of the blue-white cone about one-eighth inch from
the surface of the iron.

A cast iron rod of correct diameter, usually made
with an excess of silicon, is used by keeping its end
in contact with the molten metal and flowing it into
the puddle formed at the point of fusion. Metal
should be added so that the weld stands about one-
eighth inch above the surrounding surface of the
work.

Various forms of flux may be used and they are
applied by dipping the end of the welding rod into

128 WELDING

the powder at intervals. These powders may con-
tain borax or salt, and to prevent a hard, brittle
weld, graphite or ferro-silicon may be added. Flux
should be added only after the iron is molten and
as little as possible should be used. No flux should
be used just before completion of the work.

The welding flame should be played on the work
around the crack and gradually brought to bear on
the work. The bottom of the bevel should be joined
first and it will be noted that the cast iron tends to
run toward the flame, but does not stick together
easily. A hard and porous weld should be carefully
guarded against, as described above, and upon com-
pletion of the work the welded surface should be
scraped with a file, while still red hot, in order to
remove the surface scale.

Malleable Iron. — This material should be beveled
in the same way that cast iron is handled, and pre-
heating and slow cooling are equally desirable. The
flame used is the same as for cast iron and so is the
flux. The welding rod may be of cast iron, although
better results are secured with Norway iron wire
or else a mild steel wire wrapped with a coil of
copper wire.

It will be understood that malleable iron turns to
ordinary cast iron when melted and cooled. Welds
in malleable iron are usually far from satisfactory
and a better joint is secured by brazing the edges
together with bronze. The edges to be joined are
brought to a heat just a little below the point at
which they will flow and the opening is then quickly
filled from a rod of Tobin bronze or manganese
bronze, a brass or bronze flux being used in this
work.

OXY-ACETYLENE WELDING PRACTICE 129

Wrought Iron or Semi-Steel. — This metal should
be beveled and heated in the same way as described
for cast iron. The flame should be neutral, of the
same size as for steel, and used with the tip of the
blue-white cone just touching the work. The welding
rod should be of mild steel, or, if wrought iron is
to be welded to steel, a cast iron rod may be used.
A cast iron flux is well suited for this work. It
should be noted that wrought iron turns to ordinary
cast iron if kept heated for any length of time.

Steel. — Steel should be beveled if more than one-
eighth inch in thickness. It requires only a local
preheating around the point to be welded. The
welding flame should be absolutely neutral, without
excess of either gas. If the metal is one-sixteenth
inch or less in thickness, the tip of the blue-white
cone must be held a short distance from the surface
of the work; in all other cases the tip of this cone
is touched to the metal being welded.

The welding rod may be of mild, low carbon steel
or of Norway iron. Nickel steel rods may be used
for parts requiring great strength, but vanadium
alloys are very difficult to handle. A very satis-
factory rod is made by twisting together two wires
of the required material. The rod must be kept
constantly in contact with the work and should not
be added until the edges are thoroughly melted. The
flux may or may not be used. If one is wanted, it
may be made from three parts iron filings, six parts
borax and one part sal ammoniac.

It will be noticed that the steel runs from the
flame, but tends to hold together. Should foaming
commence in the molten metal, it shows an excess of
oxygen and that the metal is being burned.

130 WELDING

High carbon steels are very difficult to handle.
It is claimed that a drop or two of copper added to
the weld will assist the flow, but will also harden the
work. An excess of oxygen reduces the amount of
carbon and softens the steel, while an excess of acety-
lene increases the proportion of carbon and hardens
the metal. High speed steels may sometimes be
welded if first coated with semi-steel before welding.

Aluminum. — This is the most difficult of the com-
monly found metals to weld. This is caused by its
high rate' of expansion and contraction and its lia-
bility to melt and fall away from under the flame.
The aluminum seems to melt on the inside first, and,
without previous warning, a portion of the work will
simply vanish from in front of the operator's eyes.
The metal tends to run from the flame and separate
at the same time. To keep the metal in shape and
free from oxide, it is worked or puddled while in a
plastic condition by an iron rod which has been flat-
tened at one end. Several of these rods should be
at hand and may be kept in a jar of salt water while
not being used. These rods must not become coated
with aluminum and they must not get red hot while
in the weld.

The surfaces to be joined, together with the adja-
cent parts, should be cleaned thoroughly and then
washed with a 25 per cent solution of nitric acid in
hot water, used on a swab. The parts should then
be rinsed in clean water and dried with sawdust.
It is also well to make temporary fire clay moulds
back of the parts to be heated, so that the metal
may be flowed into place and allowed to cool without
danger of breakage.

Aluminum must invariably be preheated to about

OXY-ACETYLENE WELDING PRACTICE 131

600 degrees, and the whole piece being handled
should be well covered with sheet asbestos to prevent,
excessive heat radiation.

The flame is formed with an excess of acetylene
such that the second cone extends about an inch,
or slightly more, beyond the small blue-white point.
The torch should be held so that the end of this
second cone is in contact with the work, the small
cone ordinarily used being kept an inch or an inch
and a half from the surface of the work.

Welding rods of special aluminum are used and
must be handled with their end submerged in the
molten metal of the weld at all times.

When aluminum is melted it forms alumina, an
oxide of the metal. This alumina surrounds small
masses of the metal, and as it does not melt at tem-
peratures below 5000 degrees (while aluminum melts
at about 1200), it prevents a weld from being made.
The formation of this oxide is retarded and the oxide
itself is dissolved by a suitable flux, which usually
contains phosphorus to break down the alumina.

Copper. — The whole piece should be preheated and
kept well covered while welding. The flame must be
much larger than for the same thickness of steel
and neutral in character. A slight excess of acety-
lene would be preferable to an excess of oxygen, and
in all cases the molten metal should be kept envel-
oped with the flame. The welding rod is of copper
which contains phosphorus; and a flux, also contain-
ing phosphorus, should be spread for about an inch
each side of the joint. These assist in preventing
oxidation, which is sure to occur with heated copper.

Copper breaks very easily at a heat slightly under

132 WELDING

the welding temperature and after cooling it is sim-
ply cast copper in all cases.

Brass and Bronze. — It is necessary to preheat these
metals, although not to a very high temperature.
They must be kept well covered at all times to pre~
vent undue radiation. The flame should be produced
with a nozzle one size larger than for the same
thickness of steel and the small blue-white cone should
be held from one-fourth to one-half inch above the
surface of the work. The flame should be neutral
in character.

A rod or wire of soft brass containing a large per-
centage of zinc is suitable for adding to brass, while
copper requires the use of copper or manganese
bronze rods. Special flux or borax may be used to
assist the flow.

The emission of white smoke indicates that the
zinc contained in these alloys is being burned away
and the heat should immediately be turned away or
reduced. The fumes from brass and bronze welding
are very poison,ous and should not be breathed.

RESTORATION OF STEEL

The result of the high heat to which the steel has
been subjected is that it is weakened and of a dif-
ferent character than before welding. The operator
may avoid this as much as possible by first playing
the outer flame of the torch all over the surfaces
of the work just completed until these faces are all
of uniform color, after which the metal should be
well covered with asbestos and allowed to cool with-
out being disturbed. If a temporary heating oven
has been employed, the work and oven should be
allowed to cool together while protected with the

OXY-ACETYLENE WELDING PRACTICE 133

sheet asbestos. If the outside air strikes tlie freshly
welded work, even for a moment, the result will be
breakage.

A weld in steel will always leave the metal with
a coarse grain and with all the characteristics of
rather low grade cast steel. As previously men-
tioned in another chapter, the larger the grain size
in steel the weaker the metal will be, and it is the
purpose of the good workman to avoid, as far as
possible, this weakening.

The structure of the metal in one piece of steel
will differ according to the heat that it has under-
gone. The parts of the work that have been at the
melting point will, therefore, have the largest grain
size and the least strength. Those parts that have
not suffered any great rise in temperature will be
practically unaffected, and all the parts between
these two extremes will be weaker or stronger accord-
ing to their distance from the weld itself. To restore
the steel so that it will have the best grain size, the
operator may resort to either of two methods: (1)
The grain may be improved by forging. That means
that the metal added to the weld and the surfaces
that have been at the welding heat are hammered,
much as a blacksmith would hammer his finished
work to give it greater strength. The hammering
should continue from the time the metal first starts
to cool until it has reached the temperature at which
the grain size is best for strength. This temperature
will vary somewhat with the composition of the metal
being handled, but in a general way, it may be stated
that the hammering should continue without inter-
mission from the time the flame is removed from the
weld until the steel just begins to show attraction

134 WELDING

for a magnet presented to it. This temperature of
magnetic attraction will always be low enough and
the hammering should be immediately discontinued
at this point. (2) A method that is more satisfac-
tory, although harder to apply, is that of reheating
the steel to a certain temperature throughout its
whole mass where the heat has had any effect, and
then allowing slow and even cooling from this tem-
perature. The grain size is affected by the tempera-
ture at which the reheating is stopped and not by
the cooling, yet the cooling should be slow enough to
avoid strains caused by uneven contraction.

After the weld has been completed the steel must
be allowed to cool until below 1200° Fahrenheit. The
next step is to heat the work slowly until all those
parts to be restored have reached a temperature at
which the magnet just ceases to be attracted. While
the very best temperature will vary according to the
nature and hardness of the steel being handled, it
will be safe to carry the heating to .the point indi-
cated by the magnet in the absence of suitable means
of measuring accurately these high temperatures. In
using a magnet for testing, it will be most satisfac-
tory if it is an electromagnet and not of the perma-
nent type. The electric current may be secured
from any small battery and will be the means of
making sure of the test. The permanent magnet will
quickly lose its power of attraction under the com-
bined action of the heat and the jarring to which
it will be subjected.

In reheating the work it is necessary to make sure
that no part reaches a temperature above that desired
for best grain size and also to see that all parts are
brought to this temperature. Here enters the great-

OXY-ACETYLENB WELDING PRACTICE 135

est difficulty in restoring the metal. The heating
may be done so slowly that no part of the work on
the outside reaches too high a temperature and then
keeps the outside at this heat until the entire mass
is at the same temperature. A less desirable way
is to heat the outside higher than this temperature
and allow the conductivity of the metal to distribute
the excess to the inside.

The most satisfactory method, where it can be
employed, is to make use of a bath of some molten
metal or some chemical mixture that can be kept
at the exact heat necessary by means of gas fires
that admit of close regulation. The temperature of
these baths may be maintained at a constant point
by watching a pyrometer, and the finished work may
be allowed to remain in the bath until all parts have
reached the desired temperature.

WELDING INFORMATION

The following tables include much of the informa-
tion that the operator must use continually to handle
the various metals successfully. The temperature
scales are given for convenience only. The composi-
tion of various alloys will give an idea of the diffi-
culties to be contended with by consulting the infor-
mation on welding various metals. The remaining
tables are of self-evident value in this work.

136

WELDING

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OXY-ACETYLENE WELDING PRACTICE 137

METAL ALLOYS

(Society of Automobile Engineers)

Babbitt-
Tin 84.00%

Antimony 9.00%

Copper 7.00%

Brass, "White —

Copper 3.00% to 6.00%

Tin (minimum) 65.00%

Zinc : .• 28.00% to 30.00%

Brass, Red Cast —

Copper 85.00%

Tin 5.00%

Lead 5.00%

Zinc 5.00%

Brass, Yellow —

Copper 62.00% to 65.00%

Lead 2.00% to 4.00%

Zinc 36.00% to 31.00%

Bronze, Hard —

Copper 87.00% to 88.00%

Tin 9.50% to 10.50%

Zinc 1.50% to 2.50%

Bronze, Phosphor —

Copper 80.00%

Tin 10.00%

Lead 10.00%

Phosphorus 50% to .25%

Bronze, Manganese —

Copper (approximate) , 60.00%

Zinc (approximate) 40.00%

Manganese (variable) small

Bronze, Gear —

Copper 88.00% to 89.00%

Tin 11.00% to 12.00%

Phosphorus 15% to .30%

138

WELDING

Copper Zinc
8.5-7.0%
2.0-3.0% 15%
35.0%

Manganese
Not over 0.40%

Aluminum Alloys —

Aluminum

No. 1.. 90.00%

No. 2.. 80.00%

No. 3.. 65.00%

Cast Iron —

Gray Iron Malleable

Total carbon 3.0 to 3.5%

Combined carbon ...0.4 to 0.7%

Manganese 0.4 to 0.7% 0.3 to 0.7%

Phosphorus 0.6 to 1.0% Not over 0.2%

Sulphur Not over 0.1% Not over 0.6%

Silicon 1.75 to 2.25% Not over 1.0%

Carbon Steel (10 Point) —

Carbon 05% to .15%

Manganese 30% to .60%

Phosphorus (maximum) .045%

Sulphur (maximum) .05%

(20 Point) —

Carbon 15% to .25%

Manganese 30% to .60%

Phosphorus (maximum) .045%

Sulphur (maximum) .05%

(35 Point) —

Manganese 50% to .80%

Carbon 30% to .40%

Phosphorus (maximum) .05%

Sulphur (maximum) .05%

(95 Point) —

Carbon 90% to 1.05%

Manganese 25% to .50%

Phosphorus (maximum) .04%

Sulphur ' (maximum) .05%

OXY-ACETYLENE WELDING PRACTICE 139

HEATING POWER OP FUEL GASES

(In B. T. U. per Cubic Foot.)

Acetylene 1498.99 Ethylene 1562.95

Hydrogen 291.96 Methane 953.62

Alcohol 1501.76

MELTING POINTS OF METALS

Platinum 3200°

Iron, wrought 2900°

malleable 2500°

cast 2400°

pure 2760°

Steel, mild 2700°

medium 2600°

hard 2500°

Copper 1950°

Brass 1800°

Silver 1750°

Bronze ....1700°

Aluminum , 1175°

Antimony 1150°

Zinc 800°

Lead 620°

Babbitt 500-700°

Solder 500-575°

Tin 450°

NOTE. — These melting points are for average com-
positions and conditions. The exact proportion of
elements entering into the metals affects their melting
points one way or the other in practice.

140 WELDING

TENSILE STRENGTH OF METALS

Alloy steels can be made with tensile strengths as
high as 300,000 pounds per square inch. Some car-
bon steels are given below according to "points":

- Pounds per Square Inch

Steel, 10 point 50,000 to 65,000

20 point 60,000 to 80,000

40 point 70,000 to 100,000

60 point 90,000 to 120,000

Iron, Cast 13,000 to 30,000

Wrought 40,000 to 60,000

Malleable 25,000 to 45,000

Copper 24,000 to 50,000

Bronze 30,000 to 60,000

Brass, Cast 12,000 to 18,000

Boiled 30,000 to 40,000

Wire 60,000 to 75,000

Aluminum 12,000 to 23,000

Zinc 5,000 to 15,000

Tin ; 3,000 to 5,000

Lead 1,500 to 2,500

CONDUCTIVITY OF METALS

(Based on the Value of Silver as 100)

Heat Electricity

Silver 100 100

Copper 74 99

Aluminum 38 63

Brass 23 22

Zinc 19 29

Tin 14 15

OXY-ACETYLENE WELDING PRACTICE 141

Heat Electricity

Wrought Iron 12 16

Steel 11.5 12

Cast Iron 11 12

Bronze 9 7

Lead 8 9

WEIGHT OF METALS

(Per Cubic Inch)

Pounds Pounds

Lead 410 Wrought Iron 278

Copper 320 Tin 263

Bronze 313 Cast Iron 260

Brass , . .300 Zinc 258

Steel 283 Aluminum 093

EXPANSION OF METALS

(Measured in Thousandths of an Inch per Foot of

Length When Raised 1000 Degrees

in Temperature)

Inch Inch

Lead 188 Brass 115

Zinc 168 Copper 106

Aluminum 148 Steel .' 083

Silver 129 Wrought Iron 078

Bronze .118 Cast Iron.. .068

CHAPTER VI
ELECTEIC WELDING
RESISTANCE METHOD

Two distinct forms of electric welding apparatus
are in use, one producing heat by the resistance of the
metal being treated to the passage of electric cur-
rent, the other using the heat of the electric arc.

The resistance process is of the greatest use in
manufacturing lines where there is a large quantity
of one kind of work to do, many thousand pieces of
one kind, for instance. The arc method may be ap-
plied in practically any case where any other form
of weld may be made. The resistance process will be
described first.

It is a well known fact that a poor conductor of
electricity will offer so much resistance to the flow of
electricity that it will heat. Copper is a good con-
ductor, and a bar of iron, a comparatively poor con-
ductor, wh^n placed between heavy copper conductors
of a welder, becomes heated in attempting to carry the
large volume of current. The degree of heat depends
on the amount of current and the resistance of the
conductor.

In an electric circuit the ends of two pieces of
metal brought together form the point of greatest
resistance in the ' electric circuit, and the abutting
ends instantly begin to heat. The hotter this metal
becomes, the greater the resistance to the flow of cur-
rent; consequently, as the edges of the abutting ends
heat, the current is forced into the adjacent cooler

142

ELECTRIC WELDING

143

parts, until there is a uniform heat throughout the
entire mass. The heat is first developed in the inte-
rior of the metal so that it is welded there as perfectly
as at the surface.

Figure 42. — Spot Welding Machine

The electric welder (Figure .42) is built to hold the
parts to be joined between two heavy copper dies or
contacts. A current of three to five volts, but of
very great volume (amperage), is allowed to pass
across these dies, and in going through the metal to
be welded, heats the edges to a welding temperature.
It may be explained that the voltage of an electric

144 WELDING

current measures the pressure or force with which it
is being sent through the circuit and has nothing to
do with the quantity or volume passing. Amperes
measure the rate at which the current is passing
through the circuit and consequently give a measure
of the quantity which passes in any given time. Volts
correspond to water pressure measured by pounds to
the square inch ; amperes represent the flow in gallons
per minute. The low voltage used avoids all danger
to the operator, this pressure not being sufficient to
be felt even with the hands resting on the copper
contacts.

Current is supplied to the welding machine at a
higher voltage and lower amperage than is actually
used between the dies, the low voltage and high am-
perage being produced by a transformer incorporated
in the machine itself. By means of windings of suit-
able size wire, the outside current may be received at
voltages ranging from 110 to 550 and converted to the
low pressure needed.

The source of current for the resistance welder
must be alternating, that is, the current must first be
negative in value and then positive, passing from one
extreme to the other at rates varying from 25 to 133
times a second. This form is known as alternating
current, as opposed to direct current, in which there
is no changing of positive and negative.

The current must also be what is known as single
phase, that is, a current which rises from zero in value
to the highest point as a positive current and then
recedes to zero before rising to the highest point of
negative value. Two-phase of three-phase currents
would give two or three positive impulses during this
time.

ELECTRIC WELDING 145

As long as the current is single phase alternating,
the voltage and cycles (number of alternations per
second) may be anything convenient. Various volt-
ages and cycles are taken care of by specifying all
these points when designing the transformer which
is to handle the current.

Direct current is not used because there is no way
of reducing the voltage conveniently without placing
resistance wires in the circuit and this uses power
without producing useful work. Direct current may
be changed to alternating by having a direct current
motor running an alternating current dynamo, or
the change may be made by a rotary converter, al-
though this last method is not so satisfactory as the
first.

The voltage used in welding being so low to start
with, it is absolutely necessary that it be maintained
at the correct point. If the source of current supply
is not of ample capacity for the welder being used, it
will be very hard to avoid a fall of voltage when the
current is forced to pass through the high resistance
of the weld. The current voltage for various work is
calculated accurately, and the efficiency of the outfit
depends to a great extent on the voltage being con-
stant.

A simple test for fall of voltage is made by con-
necting an incandescent electric lamp across the sup-
ply lines at some point near the welder. The lamp
should burn with the same brilliancy when the weld is
being made as at any other time. If the lamp burns
dim at any time, it indicates a drop in voltage, and
this condition should be corrected.

The dynamo furnishing the alternating current
may be in the same building with the welder and

146 WELDING

operated from a direct current motor, as mentioned
above, or operated from any convenient shafting or
source of power. When the dynamo is a part of the
welding plant it should be placed as close to the
welding machine as possible, because the length of
the wire used affects the voltage appreciably.

In order to hold the voltage constant, the Toledo
Electric Welder Company has devised connections
which include a rheostat to insert a variable resist-
ance in the field windings of the dynamo so that the
voltage may be increased by cutting this resistance
out at the proper time. An auxiliary switch is con-
nected to the welder switch so that both switches act
together. When the welder switch is closed in mak-
ing a weld, that portion of the rheostat resistance
between two arms determining the voltage is short
circuited. This lowers the resistance and the field
magnets of the dynamo are made stronger so that
additional voltage is provided to care for the re-
sistance in the metal being heated.

A typical machine is shown in the accompanying
cut (Figure 43). On top of the welder are two jaws
for holding the ends of the pieces to be welded. The
lower part of the jaws is rigid while the top is
brought down on top of the work, acting as a clamp.
These jaws carry the copper dies through which the
current enters the work being handled. After the
work is clamped between the jaws, the upper set
is forced closer to the lower set by a long com-
pression lever. The current being turned on with
the surfaces of the work in contact, they immedi-
ately heat to the welding point when added pressure
on the lever forces them together and completes the
weld.

ELECTRIC WELDING

147

148 WELDING

The transformer is carried in the base of the ma-
chine and on the left-hand side is a regulator for
controlling the voltage for various kinds of work. The
clamps are applied by treadles convenient to the foot

Figure 43a. — Method of Testing Electric Welder

of the operator. A treadle is provided which instantly
releases both jaws upon the completion of the weld.

Figure 44. — Detail of Water-Cooled Spot Welding Head

One or both of the copper dies may be cooled by a
stream of water circulating through it from the city
water mains (Figure 44). The regulator and switch
give the operator control of the heat, anything from

ELECTRIC WELDING

149

a dull red to the melting point being easily obtained
by movement of the lever (Figure 45).

Welding. — It is not necessary to give the metal '
to be welded any special preparation, although when
very rusty or covered with scale, the rust and scale

Figure 45. — Welding Head of a Water-Cooled Welder

should be removed sufficient^ to allow good contact
of clean metal on the copper dies. The cleaner and
better the stock, the less current it takes, and there
is less wear on the dies. The dies should be kept
firm and tight in their holders to make a good contact.
All bolts and nuts fastening the electrical contacts
should be clean and tight at all times.

150 WELDING

The scale may be removed from forcings by im-
mersing them in a pickling solution in a wood, stone
or lead-lined tank.

The solution is made with five gallons of commer-
cial sulphuric acid in 150 gallons of water. To get
the quickest and best results from this method, the
solution should be kept as near the boiling point as
possible by having a coil of extra heavy lead pipe
running inside the tank and carrying live steam. A
very few minutes in this bath will remove the scale
and the parts should then be washed in running
water. After this washing they should be dipped into
a bath of 50 pounds of unslaked lime in 150 gallons
of water to neutralize any trace of acid.

Cast iron cannot be commercially welded, as it is
high in carbon and silicon, and passes suddenly from
a crystalline to a fluid state when brought to the weld-
ing temperature. With steel or wrought iron the
temperature must be kept below the melting point to
avoid injury to the metal. The metal must be heated
quickly and pressed together with sufficient force to
push all burnt metal out of the joint.

High carbon steel can be welded, but must be an-
nealed after welding to overcome the strains set up
by the heat being applied at one place. Good results
are hard to obtain when the carbon runs as high as
75 points, and steel of this class can only be handled
by an experienced operator. If the steel is below 25
points in carbon content, good welds will, always be
the result. To weld high carbon to low carbon steel,
the stock should be clamped in the dies with the low
carbon stock sticking considerably further out from
the die than the high carbon stock. Nickel steel welds
readily, the nickel increasing the strength of the weld.

ELECTRIC WELDING 151

Iron and copper may be welded together by reduc;
ing the size of the copper end where it comes in con-
tact with the iron. When welding copper and brass
the pressure must be less than when welding iron.
The metal is allowed to actually fuse or melt at the
juncture and the pressure must be sufficient to force
the burned metal out. The current is cut off the
instant the metal ends begin to soften, this being
done by means of an automatic switch which opens
when the softening of the metal allows the ends to
come together. The pressure is applied to the weld
by having the sliding jaw moved by a weight on the
end of an arm.

Copper and brass require a larger volume of cur-
rent at a lower voltage than for steel and iron. The
die faces are set apart three times the diameter o£
the stock for "brass and four times the diameter for
copper.

Light gauges of sheet steel can be welded to heavy
gauges or to solid bars of steel by "spot" welding,
which will be described later. Galvanized iron can.
be welded, but the zinc coating will be burned off.
Sheet steel can be welded to cast iron, but will pull
apart, tearing out particles of the iron.

Sheet copper and sheet brass may be welded, al-
though this work requires more experience than with
iron and steel. Some grades of sheet aluminum -can
be spot-welded if the slight roughness left on the sur-
face under the die is not objectionable.

Butt Welding. — This is the process which joins the
ends of two pieces of metal as described in the fore-
going part of this chapter. The ends are in plain
sight of the operator at all times and it can easily be
seen when the metal reaches the welding heat and

152

WELDING

begins to soften (Figure 46). It is at this point
that the pressure must be applied with the lever and
the ends forced together in the weld.

The parts are placed in the clamping jaws (Figure
47) with y$ to y% inch of metal extending beyond the

Figure 46. — Butt Welder

jaw. The ends of the metal touch each other and
the current is turned on by means of a switch. To
raise the ends to the proper heat requires from 3
seconds for 34 -inch rods to 35 seconds for a l-5/2-inch
bar.

This method is applicable to metals having prac-
tically the same area of metal to be brought into con-
tact on each end. When such parts are forced to-

ELECTRIC WELDING

153

gether a slight projection will be left in the form
of a fin or an enlarged portion called an upset. The
degree of heat required for any work is found by
moving the handle of the regulator one way or the
other while testing several parts. When this setting

Figure 47. — Clamping Dies of a Butt Welder

is right the work can continue as long as the same
sizes are being handled.

Copper, brass, tool steel and all other metals that
are harmed by high temperatures must be heated
quickly and pressed together with sufficient force to
force all burned metal from the weld.

In case it is desired -to make a weld in the form
of a capital letter T, it is necessary to heat the part
corresponding to the top bar of the T to a bright red,
then bring the lower bar to the pre-heated one and

154 WELDING

again turn on the current, when a weld can be
quickly made.

Spot Welding. — This is a method of joining metal
sheets together at any desired point by a welded spot
about the size of a rivet. It is done on a spot welder
by fusing the metal at the point desired and at the
same instant applying sufficient pressure to force the
particles of molten metal together. The dies are usu-
ally placed one above the other so that the work may
rest on the lower one while the upper one is brought
down on top of the upper sheet to be welded.

One of the dies is usually pointed slightly, the op-
posing one being left flat. The pointed die leaves a
slight indentation on one side of the metal, while the
other side is left smooth. The dies may be reversed
so that the outside surface of any work may be left
smooth. The current is allowed to flow through the
dies by a switch which is closed after pressure is
applied to the work.

There is a limit to the thickness of sheet metal that
can be welded by this process because of the fact
that the copper rods can only carry a certain quantity
of current without becoming unduly heated them-
selves. Another reason is that it is difficult to make
heavy sections of metal touch at the welding point
without excessive pressure.

Lap welding is the process used when two pieces of
metal are caused to overlap and when brought to a
welding heat are forced together by passing through
rollers, or under a press, thus leaving the welded joint
practically the same thickness as the balance of the
work.

Where it is desirable to make a continuous seam, a
special machine is required, or an attachment for

ELECTRIC WELDING 155

one of the other types. In this form of work the
stock must be thoroughly cleaned and is then passed
between copper rollers which act in the same capacity
as the copper dies.

Other Applications. — Hardening and tempering can
be done by clamping the work in the welding dies and
setting the control and time to bring the metal to the
proper color, when it is cooled in the usual manner.

Brazing is done by clamping the work in the jaws
and heating until the flux, then the spelter has melted
and run into the joint. Riveting and heading of
rivets can be done by bringing the dies down on oppo-
site ends of the rivet after it has been inserted in
the hole, the dies being shaped to form the heads
properly.

Hardened steel may be softened and annealed so
that it can be machined by connecting the dies of
the welder to each side of the point to be softened.
The current is then applied until the work has
reached a point at which it will soften when cooled. /

Troubles and Remedies. — The following methods
have been furnished by the Toledo Electric Welde.r
Company and are recommended for this class of work
whenever necessary.

To locate grounds in the primary or high voltage
side of the circuit, connect incandescent lamps in
series by means of a long piece of lamp cord, as shown,
in Figure 43a. For 110 volts use one lamp, for
220 volts use two lamps and for 440 volts use four
lamps. Attach one end of the lamp cord to one side
of the switch, and close the switch. Take the other
end of the cord in the hand and press it against
some part of the welder frame where the metal is
clean and bright. Paint, grease and dirt act as in-

156 WELDING

sulators and prevent electrical contact. If the lamp
lights, the circuit is in electrical contact with the
frame; in other words, grounded. If the lamps do
not light, connect the wire to a terminal block, die or
slide. If the lamps then light, the circuit, coils or
leads are in electrical contact with the large coil in
the transformer or its connections.

If, however, the lamps do not light in either case,
the lamp cord should be disconnected from the switch
and connected to the other side, and the operations
of connecting to welder frame, dies, terminal blocks,
etc., as explained above, should be repeated. If the
lamps light at any of these connections, a "ground"
is indicated. "Grounds" can usually be found by
carefully tracing the primary circuit until a place
is found \yhere the insulation is defective. Reinsulate
and make the above tests again to make sure every-
thing is clear. If the ground can not be located by
observation, the various parts of the primary circuit
should be disconnected, and the transformer, switch,
regulator, etc., tested separately.

. To locate a ground in the regulator or other part,
disconnect the lines running to the welder from the
switch. The test lamps used in the previous tests are
connected, one end of lamp cord to the switch, the
other end to a binding post of the regulator. Connect
the other side of the switch to some part of the regu-
lator housing. (This must be a clean connection to
a bolt head or the paint should be scraped off.) Close
the switch. If the lamps light, the regulator winding
or some part of the switch is "grounded" to the iron
base or core of the regulator. If the lamps do not
light, this part of the apparatus is clear.

This test can be easily applied to any part of the

ELECTRIC WELDING 157

welder outfit by connecting to the current carrying
part of the apparatus, and to the iron base or frame
that should not carry current. If the lamps light, it
indicates that the insulation is broken down or is
defective.

An A. C. voltmeter can, of course, be substituted
for the lamps, or a D. C. voltmeter with D. C. cur-
rent can be used in making the tests.

A short circuit in the primary is caused by the in-
sulation of the coils becoming defective and allow-
ing the bare copper wires to touch each other. This
may result in a "burn out" of one or more of the
transformer coils, if the trouble is in the transformer,
or in the continued blowing of fuses in the line. Feel
of each coil separately. If a short circuit exists in a
coil it will heat excessively. Examine all the wires ;
the insulation may have worn through and two of
them may cross, or be in contact with the frame or
other part of the welder. A short circuit in the regu-
lator winding is indicated by failure of the apparatus
to regulate properly, and sometimes, though not al-
ways, by the heating of the regulator coils

The remedy for a short circuit is to reinsulate the
defective parts. It is a good plan to prevent trouble
by examining the wiring occasionally and see that the
insulation is perfect.

To Locate Grounds and Short Circuits in the
Secondary, or Low Voltage Side. — Trouble of this
kind is indicated by the machine acting sluggish or,
perhaps, refusing to operate. To make a test, it will
be necessary to first ascertain the exciting current of
your particular transformer. This is the current the
transformer draws on ( ' open circuit, ' ' or when sup-
plied with current from the line with no stock in

158 WELDING

the welder dies. The following table will give this
information close enough for all practical purposes:

-LV. VV .

Rating

110 Volts

220 Volts

440 Volts

550 Volts

3

1.5

.75

.38

.3

5

2.5

1.25

.63

.5

8

3.6

1.8

.9

.72

10

4.25

2.13

1.07

.85

15

6.

3.

1.5

1.2

20

7.

3.5

1.75

1.4

30

9.

4.5

2.25

1.8

35

9.6

4.8

2.4

1.92

50

10.

5.

2.5

2.

Remove the fuses from the wall switch and substi-
tute fuses just large enough to carry the " exciting '"'
current. If no suitable fuses are at hand, fine strands
of copper from an ordinary lamp cord may be used.
These strands are usually No. 30 gauge wire and will
fuse at about 10 amperes. One or more strands
should be used, depending on the amount of exciting
current, and are connected across the fuse clips in
place of fuse wire. Place a piece of wood or fibre
between the welding dies in the welder as though
you were going to weld them. See that the regulator
is on the highest point and close the welder switch.
If the secondary circuit is badly grounded, current
will flow through the ground, and the small fuses or
small strands of wire will burn out. This is an indi-
cation that both sides of the secondary circuit are
grounded or that a short circuit exists in a primary
coil. In either case the welder should not be oper-
ated until the trouble is found and removed. If,
however, the small fuses do not "blow/7 remove same

ELECTRIC WELDING 159

and replace the large fuses, then disconnect wires
running from the wall switch to the welder and sub-
stitute two pieces of No. 8 or No. 6 insulated copper
wire, after scraping off the insulation for an inch or
two at each end. Connect one wire from the switch to
the frame of welder; this will leave one loose end.
Hold this a foot or so away from the place where
the insulation is cut off ; then turn on the current and
strike the free end of this wire lightly against one of
the copper dies, drawing it away quickly. If no
sparking is produced, the secondary circuit is free
from ground, and you will then look for a broken
connection in the circuit. Some caution must be
used in making the above test, as in case one terminal
is heavily grounded the testing wire may be fused if
allowed to stay in contact with the die.

The Remedy. — Clean the slides, dies and terminal
blocks thoroughly and dry out the fibre insulation if
it is damp. See that no scale or metal has worked
under the sliding parts, and that the secondary leads
do not touch the frame. If the ground is very heavy
it may be necessary to remove the slides in order to
facilitate the examination and removal of the ground.
Insulation, where torn or worn through, must be care-
fully replaced or taped. If the transformer coils are
grounded to the iron core of the transformer or to
the secondary, it may be necessary to remove the coils
and reinsulate them at the points of contact. A short
circuited coil will heat excessively and eventually
burn out. This may mean a new coil if you are unable
to repair the old one. In all cases the transformer
windings should be protected from mechanical injury
or dampness. Unless excessively overloaded, trans-
formers will last for years without giving a moment 's

160 WELDING

trouble, if they are not exposed to moisture or are
not injured mechanically.

The most common trouble arises from poor electrical
contacts, and they are the cause of endless trouble and
annoyance. See that all connections are clean and
bright. Take out the dies every day or two and see
that there is no scale, grease or dirt between them
and the holders. Clean them thoroughly before re-
placing. Tighten the bolts running from the trans-
former leads to the work jaws.

ELECTRIC ARC WELDING

This method bears no relation to the one just con-
sidered, except that the source of heat is the same in
both cases. Arc welding makes use of the flame
produced by the voltaic arc in practically the same
way that oxy-acetylene welding uses the flame from
the gases.

If the ends of two pieces of carbon through which a
current of electricity is flowing while they are in con-
tact are separated from each other quite slowly, a
brilliant arc of flame is formed between them which
consists mainly of carbon vapor. The carbons are
consumed by combination with the oxygen in the air
and through being turned to a gas under the intense
heat.

The most intense action takes place at the center of
the carbon which carries the positive current and this
is the point of greatest heat. The temperature at this
point in the arc is greater than can be produced by
any other means under human control.

An arc may be formed between pieces of metal,
called electrodes, in the same way as between carbon.

ELECTRIC WELDING 161

The metallic arc is called a flaming arc and as the
metal of the electrode burns with the heat, it gives the
flame a color characteristic of the material being used.
The metallic arc may be drawn out to a much greater
length than one formed between carbon electrodes.

Arc welding is carried out by drawing a piece of
carbon which is of negative polarity away from the
pieces of metal to be welded while the metal is made
positive in polarity. The negative wire is fastened
to the carbon electrode and the work is laid on a
table made of cast or wrought iron to which the posi-
tive wire is made fast. The direction of the flame is
then from the metal being welded to the carbon and
the work is thus prevented from being saturated
with carbon, which would prove very detrimental to
its strength. A secondary advantage is found in the
fact that the greatest heat is at the metal being welded
because of its being the positive electrode.

The carbon electrode is usually made from one
quarter to one and a half inches in diameter and from
six to twelve inches in length. The length of the arc
may be anywhere from one inch to four inches, de-
pending on the size of the work being handled.

While the parts are carefully insulated to avoid
danger of shock, it is necessary for the operator to
wear rubber gloves as a further protection, and to
wear some form of hood over the head to shield him
against the extreme heat liberated. This hood may
be made from metal, although some material that does
not conduct electricity is to be preferred. The work
is watched through pieces of glass formed with one
sheet, which is either blue or green, placed over an-
other which is red. Screens of glass are sometimes
used without the head protector. Some protection ,

162 WELDING

for the eyes is absolutely necessary because of the
intense white light.

It is seldom necessary to preheat the work as with
the gas processes, because the heat is localized at the
point of welding and the action is so rapid that the
expansion is not so great. The necessity of pre-
heating, however, depends entirely on the material,
form and size of the work being handled. The same
advice applies to arc welding as to the gas flame
method but in a lesser degree. Filling rods are used
in the same way as with any other flame process.

It is the purpose of this explanation to state the
fundamental principles of the application of the elec-
tric arc to welding metals, and by applying the prin-
ciples the following questions will be answered :

What metals can be welded by the electric arc?

"What difficulties are to be encountered in applying
the electric arc to welding?

What is the strength of the weld in comparison with
the original piece?

What is the function of the arc welding machine
itself?

What is the comparative application of the electric
arc and the oxy-acetylene method and others of a
similar nature ?

The answers to these questions will make it possi-
ble to understand the application of this process to
any work. In a great many places the use of the arc
is cutting the cost of welding to a very small frac-
tion of what it would be by any other method, so
that the importance of this method may be well un-
derstood.

Any two metals which are brought to the melting
temperature and applied to each other will adhere so

ELECTRIC WELDING f 163

that they are no more apt to break at the weld than
at any other point outside of the weld. It is the
property of all metals to stick together under these
conditions. The electric arc is used in this connec-
tion merely as a heating agent. This is its only func-
tion in the process.

It has advantages in its ease of application and the
cheapness with which heat can be liberated at any
given point by its use. There is nothing in connec-
tion with arc welding that the above principles will
not answer; that is, that metals at the melting point
will weld and that the electric arc will furnish the
heat to bring them to this point. As to the first ques-
tion, wrhat metals can be welded, all metals can be
welded.

The difficulties which are encountered are as fol-
lows :

In the case of brass or zinc, the metals will be cov-
ered with a coat of zinc oxide before they reach a
welding heat. This Zinc oxide makes it impossible for
two clean surfaces to come together and some method
has to be used for eliminating this possibility and
allowing the two surfaces to join without the possi-
bility of the oxide intervening. The same is true of
aluminum, in which the oxide, alumina, will be
formed, and with several other alloys comprising ele-
ments of different melting points.

In order to eliminate these oxides, it is necessary
in practical work, to puddle the weld ; this is, to have
a sufficient quantity of molten metal at the weld so
that the oxide is floated away. When this is done,
the two surfaces which are to be joined are covered
with a coat of melted metal on which floats the oxide
and other impurities. The two pieces are thus allowed

164 WELDING

to join while their surfaces are protected. This pre-
caution is not necessary in working with steel except
in extreme cases.

Another difficulty which is met with in the welding
of a great many metals is their expansion under heat,
which results in so great a contraction when the weld
cools that the metal is left with a considerable strain
on it. In extreme cases this will result in cracking
at the weld or near it. To eliminate this danger it
is necessary to apply heat either all over the piece to
be welded or at certain points. In the case of cast
iron and sometimes with copper it is necessary to
anneal after welding, since otherwise the welded
pieces will be very brittle on account of the chilling.
This is also true of malleable iron.

Very thin metals which are welded together and
are not backed up by something to carry away the
excess heat, are very apt to burn through, leaving a
hole where the weld should be. This difficulty can
be eliminated by backing up the weld with a metal
face or by decreasing the intensity of the arc so that
this melting through will not' occur. However, the
practical limit for arc welding without backing up
the work with a metal face or decreasing the intensity
of the arc is approximately 22 gauge, although thin-k
ner metal can be welded by a very skillful and care-
ful operator. ,

One difficulty with arc welding is the lack of skill-
ful operators. This method is often looked upon as
being something out of the ordinary and governed by
laws entirely different from other welding. As a
matter of fact, it does not take as much skill to make
a good arc weld as it does to make a good weld in a
forge fire as the blacksmith does it. There are few

ELECTRIC WELDING 165

jobs which cannot be handled successfully by an oper-
ator of average intelligence with one week's instruc-
tions, although his work will become better and better
in quality as he continues to use the arc.

Now comes the question of the strength of the weld
after it has been made. This strength is equally as
great as that of the metal that is used to make the
weld. It should be remembered, however, that the
metal which goes into the weld is put in there as a
casting and has not been rolled. This would make
the strength of the weld as great as the same metal
that is used for filling if in the cast form.

Two pieces of steel could be welded together hav-
ing a tensile strength at the weld of 50,000 pounds.
Higher strengths than this can be obtained by the
use of special alloys for the filling material or by
rolling. Welds with a tensile strength as great as
mentioned will give a result which is perfectly satis-
factory in almost all cases.

There are a great many jobs where it is possible to
fill up the weld, that is, make the section at the point
of the weld a little larger than the section through the
the rest of the piece. By doing this, the disadvantages
of the weld being in the form of a casting in compari-
son with the rest of the piece being in the form of*
rolled steel can be overcome, and make the weld itself
even stronger than the original piece.

The next question is the adaptability of the electric
arc in comparison with forge fire, oxy-acetylene or
other method. The answer is somewhat difficult if
made general. There are no doubt some cases where
the use of a drop hammer and forge fire or the use of
the oxy-acetylene torch will make, all things being
considered, a better job than the use of the electric

lt>6 WELDING

arc, although a case where this is absolutely proved is
rare.

The electric arc will melt metal in a weld for less
than the same metal can be melted by the use of the
oxy-acetylene torch, and, on account of the fact that
the heat can be applied exactly where it is required
and in the amount required, the arc can in almost all
cases supply welding heat for less cost than a forge
fire or heating furnace.

The one great advantage of the oxy-acetylene
method in comparison with other methods of welding
is the fact that in some cases of very thin sheet, the
weld can be made somewhat sooner than is possible
otherwise. With metal of 18 gauge or thicker, this
advantage is eliminated. In cutting steel, the oxy-
acetylene torch is superior to almost any other pos-
sible method.

Arc Welding Machines. — A consideration of the
function and purpose of the various types of arc weld-
ing machines shows that the only reason for the use
of any machine is either for conversion of the cur-
rent from alternating to direct, or, if the current is
already direct, then the saving in the application of
this current in the arc.

It is practically out of the question to apply an
alternating current arc to welding for the reason that
in any arc practically all the heat is liberated at the
positive electrode, which means that, in alternating
current, half the heat is liberated at each electrode
as the current changes its direction of flow or alter-
nates. Another disadvantage of the alternating arc is
that it is difficult of control and application.

In all arc welding by the use of the carbon arc,
the positive electrode is made the piece to be welded,

ELECTRIC WELDING 167

while in welding with metallic electrodes this may
be either the piece to be welded of the rod that is
used as a filler. The voltage across the arc is a vari-
able quantity, depending on the length of the flame,
its temperature and the gases liberated in the arc.
With a carbon electrode the voltage will vary from
zero to forty-five volts. With the metallic electrode
the voltage will vary from zero to thirty volts. It is,
therefore, necessary for the welding machine to be
able to furnish to the arc the requisite amount of cur-
rent, this amount being varied, and furnish it at all
times at the voltage required.

The simplest welding apparatus is a resistance in
series with the arc. This is entirely satisfactory in
every way except in cost of current. By the use of
resistance in series with the arc and using 220 volts
as the supply, from eighty to ninety per cent of the
current is lost in heat at the resistance. Another
disadvantage is the fact that most materials change
their resistance as their temperature changes, thus
making the amount of current for the arc a variable
quantity, depending on the temperature of the resist-
ance.

There have been various methods originated for
saving the power mentioned and a good many ma-
chines have been put on the market for this pur-
pose. All of them save some power over what a plain
resistance would use. Practically all arc welding ma-
chines at the present time are motor generator sets,
the motor of which is arranged for the supply volt-
age and current, this motor being direct connected to
a compound wound generator delivering approxi-
mately seventy-five volts direct current. Then by the
use of a resistance, this seventy-five volt supply is

168 WELDING

applied to the arc. Since the voltage across the arc
will vary from zero to fifty volts, this machine will
save from zero up to seventy per cent of the power
that the machine delivers. The rest of the power, of
course, has to be dissipated in the resistance used in
series with the arc.

A motor generator set which can be purchased from
any electrical company, with a long piece of fence wire
wound around a piece of asbestos, gives results equally
as good and at a very small part of the first cost.

It is possible to construct a machine which will
eliminate all losses in the resistance; in other words,
eliminate all resistance in series with the arc. A
machine of this kind will save its cost within a very
short time, providing the welder is used to any extent.

Putting it in figures, the results are as follows for
average conditions. Current at 2c per kilowatt hour,
metallic electrode arc of 150 amperes, carbon arc 500
amperes ; voltage across the metallic electrode arc 20,
voltage across the carbon arc 35. Supply current 220
volts, direct. In the case of the metallic electrode, if
resistance is used, the cost of running this arc is sixty-
six cents per hour. With the carbon electrode, $2.20
per hour. If a motor generator set with a seventy
volt constant potential machine is used for a welder,
the cost will be as follows:

Metallic electrode 25.2c. Carbon electrode 84c per
hour. With a machine which will deliver the required
voltage at the arc and eliminate all the resistance in
series with the arc, the cost will be as follows : Me-
tallic electrode 7.2c per hour; carbon electrode 42c
per hour. This is with the understanding that the
arc is held constant and continuously at its full value.
This, however, is practically impossible and the actual

ELECTRIC WELDING

load factor is approximately fifty per cent, wiiich
would mean that operating a welder as it is usually
operated, this result will be reduced to one-half of
that stated in all cases.

CHAPTER VII
HAND FOEGING AND WELDING

Smithing, or blacksmithing, is the process of work-
ing heated iron, steel or other metals by forging, bend-
ing or welding them.

The Forge. — The metal is heated in a forge con-
sisting of a shallow pan for holding the fire, in the
center of which is an opening from below through
which air is forced to make a hot fire.

Figure 48. — Tuyere Construction on a Forge

Air is forced through this hole, called a " tuyere "
(Figure 48) by means of a hand bellows, a rotary
fan operated with crank or lever, or with a fan driven
from an electric motor. The harder the air is driven
into the fire above the tuyere the more oxygen is fur-
nished and the hotter the fire becomes.

Directly below the tuyere is an opening through
which the ashes that drop from the fire may be cleaned
out.

170

HAND FORGING AND WELDING 171

The Fire. — The fire is made by placing a small
piece of waste soaked in oil, kerosene or gasoline, over
the tuyere, lighting the waste, then starting the fan
or blower slowly. Gradually cover the waste, while
it is burning brightly, with a layer of soft coal. The
coal will catch fire and burn after the waste has been
consumed. A piece of waste half the size of a per-
son's hand is ample for this purpose.

The fuel should be "smithing coal." A lump of
smithing coal breaks easily, shows clean and even on
all sides and should not break into layers. The coal
is broken into fine pieces and wet before being used
on the fire.

The fire should be kept deep enough so that there is
always three or four inches of fire below the piece of
metal to be heated and there should be enough fire
above the work so that no part of the metal being
heated comes in contact with the air. The fire should
be kept as small as possible while following these rules
as to depth.

To make the fire larger, loosen the coal around the
edges. To make the fire smaller, pack wet coal around
the edges in a compact mass and loosen the fire in
the center. Add fresh coal only around the edges of
the fire. It will turn to coke and can then be raked
onto the fire. Blow only enough air into the fire to
keep it burning brightly, not so much that the fire is
blown up through the top of the coal pack. To pre-
vent the fire from going out between jobs, stick a piece
of soft wood into it and cover with fresh wet coal.

Tools. — The hammer is a ball pene, or blacksmith 's
hammer, weighing about a pound and a half.

The sledge is a heavy hammer, weighing from 5 to
20 pounds and having a handle 30 to 36 inches long.

172

WELDING

The anvil is a heavy piece of wronght iron (Figure
49), faced with steel and having four legs. It has a
pointed horn on one end, an overhanging tail on the
other end and a flat top. In the tail there is a square
hole called the " bardie" hole and a round one called
the "spud" hole.

Tongs, with handles about one foot long and jaws
suitable for holding the work, are used. To secure a
firm grip on the work, the jaws may be heated red

Figure 49. — Anvil, Showing Horn, Tail, Hardie Hole and Spud Hole

hot and hammered into shape over the piece to be
held, thus giving a properly formed jaw. Jaws should
touch the work along their entire length.

The set hammer is a hammer, one end of whose head
is square and flat, and from this face the head tapers
evenly to the other face. The large face is about l!/4
inches square.

The flatter is a hammer having one face of its head
flat and about 2~y2 inches square.

Swages are hammers having specially formed faces
for finishing rounds, squares, hexagons, ovals, tapers,
etc.

HAND FORGING AND WELDING 173

Fullers are hammers having a rounded face, long
in one direction. They are used for spreading metal
in one direction only.

The hardy is a form of chisel with a short, square
shank which may be set into the hardie hole for cut-
ting off hot bars.

Operations. — Blacksmithing consists of bending,
drawing or upsetting with the various hammers, or
in punching holes.

Bending is done over the square corners of the
anvil if square cornered bends are desired, or over the
horn of the anvil if rounding bends, eyes, hooks, etc.,
are wanted.

To bend a ring or eye in the end of a bar, first figure
the length of stock needed by multiplying the diam-
eter of the hole by 31/7, then heat the piece to a
good full red at a point this distance back from the
end. Next bend the iron over at a 90 degree angle
(square) at this point. Next, heat the iron from
the bend just made clear to the point and make the
eye by laying the part that was bent square over the
horn of the anvil and bending the extreme tip into
part of a circle. Keep pushing the piece farther and
farther over the horn of the anvil, bending it as you
go. Do not hammer directly over the horn of the
anvil, but on the side where you are doing the
bending.

To make the outside of a bend square, sharp and
full, rather than slightly rounding, the bent piece
must be laid edgewise on the face of the anvil. That
is, after making the bend over the corner of the anvil,
lay the piece on top of the anvil so that its edge and
not the flat side rests on the anvil top. With the work
in this position, strike directly against the corner

174 WELDING

with the hammer so that the blows come in line, first
with one leg of the work, then the other, and always
directly on the corner of the piece. This operation
cannot be performed by laying the w^ork so that one
leg hangs over the anvil's corner.

To make a shoulder on a rod or bar, heat the work
and lay flat across the top of the anvil with the point
at which the shoulder is desired at the edge of the
anvil. Then place the set hammer on top of the piece,
with the outside edge of the set hammer directly over
the edge of the anvil. While hammering in this posi-
tion keep the work turning continually.

To draw stock means to make it longer and thinner
by hammering. A piece to be drawn out is usually
laid across the horn of the anvil while being struck
with the hammer. The metal is then spread in only
one direction in place of being spread in every direc-
tion, as it would be if laid on the anvil face. To
draw the work, heat it to as high a temperature as it
will stand without throwing sparks and burning. The
fuller may be used for drawing metal in place of lay-
ing the work over the horn of the anvil.

When drawing round stock, it should be first drawn
out square, and when almost down to size it may be
rounded. When pointing stock, the same rule of first
drawing out square applies.

Upsetting means to make a piece shorter in length
and greater in thickness or width, or both shorter and
thicker. To upset short pieces, heat to a bright red at
the place to be upset, then stand on end on the anvil
face and hammer directly down on top until of the
right form. Longer pieces may be swung against the
anvil or placed upright on a heavy piece of metal
lying on the floor or that is sunk into the floor. While

HAND FORGING AND WELDING 175

standing on this heavy piece the metal may be upset
by striking down on the end with a heavy hammer or
the sledge. If a bend appears while upsetting, it
should be straightened by hammering back into shape
on the anvil face.

Light blows affect the metal for only a short dis-
tance from the point of striking, but heavy blows tend
to swell the metal more equally through its entire
length. In driving rivets that should fill the holes,
heavy blows should be struck, but to shape the end of
a rivet or to make a head on a rod, light blows should
be used.

The part of the piece that is heated most will upset
the most.

To punch a hole through metal, use a tool steel
punch with its end slightly tapering to a size a little
smaller than the hole to be punched. The end of
the punch must be square across and never pointed or
rounded.

First drive the punch part way. through from one
side and then turn the work over. When you turn
it over, notice where the bulge appears and in that
way locate the hole and drive the punch through from
the second side. This makes a cleaner and more even
hole than to drive completely through from one side.
When the punch is driven , in from the second side,
the place to be punched through • should be laid over
the spud hole in the tail of the anvil and the piece
driven out of the work.

Work when hot is larger than it will be after cool-
ing. This must be remembered when fitting parts or
trouble will result. A two-foot bar of steel will be
!/4 inch longer when red hot than when cold.

176 WELDING

The temperatures of iron correspond to the fol-
lowing colors :

Dullest red seen in the dark 878°

Dullest red seen in daylight 887°

Dull red 1100°

Full red 1370°

Light red 1550°

Orange 1650°

Light orange 1725°

Yellow 1825°

Light yellow 1950°

Bending Pipes and Tubes. — It is difficult to make
bends or curves in pipes and tubing without leaving
a noticeable bulge at some point of the work. Seam-
less steel tubing may be handled without very great
danger of this trouble if care is used, but iron pipe,
having a seam running lengthwise, must be given
special attention to avoid opening the seam.

Bends may be made without kinking if the tube or
pipe is brought to a full red heat all the way around
its circumference and at the place where the bend
is desired. Hold the cool portion solidly in a vise
and, by taking hold of the free end, bend very slowly
and with a steady pull. The pipe must be kept at
full red heat with the flames from one or more torches
and must not be hammered to produce the bend.
If a sufficient purchase cannot be secured on the free
end by the hand, insert a piece of rod or a smaller
pipe into the opening.

While making the bend, should small bulges appear,
they may be hammered back into shape before pro-
ceeding with the work.

HAND FORGING AND WELDING 177

Tubing or pipes may be bent while being held
between two flat metal surfaces while at a bright
red heat. The metal plates at each side of the work
prevent bulging.

Another method by which tubing may be bent
consists of filling completely with tightly packed sand
and fitting a solid cap or plug at each end.

Thin brass tubing may be filled with melted resin
and may be bent after the resin cools. To remove
the, resin it is necessary to heat the tube, allowing
it to run out.

Large jobs of bending should be handled in special
pipe bending machines in which the work is forced
through formed rolls which prevent its bulging.

WELDING

Welding with the heat of a blacksmith forge fire,
or a coal or illuminating gas fire, can only be per-
formed with iron and steel because of the low heat
which is not localized as with the oxy-acetylene and
electric processes. Iron to be welded "in this manner
is heated until it reaches the temperature indicated
by an orange color, not white, as is often stated, this
orange color being slightly above 1600 degrees Fah-
renheit. Steel is usually welded at a bright red heat
because of the danger of oxidizing or burning the
metal if the temperature is carried above this point.

The Fire. — If made in a forge, the fire should be
built from good smithing coal or, better still, from
coke. Gas fires are, of course, produced by suitable
burners and require no special preparation except
adjustment of the heat to the proper degree for the
size and thickness of the metal being welded so that
it will not be burned.

178 WELDING

A coal fire used for ordinary forging operations
should not be used for welding because of the im-
purities it contains. A fresh fire should be built
with a rather deep bed of coal, four to eight inches
being about right for work ordinarily met with. The
fire should be kept burning until the coal around the
edges has been thoroughly coked and a sufficient
quantity of fuel should be on and around the fire
so that no fresh coal will have to be added while
working.

After the coking process has progressed sufficiently,
the edges should be packed down and the fire made
as small as possible while still surrounding the ends
to be joined. The fire should not be altered by poking
it while the metal is being heated. The best form
of fire to use is one having rather high banks of
coked coal on each side of the mass, leaving an open-
ing or channel from end to end. This will allow the
added fuel to be brought down on top of the fire
with a small amount of disturbance.

Preparing to Weld. — If the operator is not familiar
with the metal to be handled, it is best to secure a
test piece if at all possible and try heating it and
joining the ends. Various grades of iron and steel
call for different methods of handling and for dif-
ferent degrees of heat, the proper method and tem-
perature being determined best by actual test under
the hammer.

The form of the pieces also has a great deal to do
with their handling, especially in the case of a more
or less inexperienced workman. If the pieces are
at all irregular in shape, the motions should be gone
through with before the metal is heated and the best
positions on the anvil as well as in the fire deter-

HAND FORGING AND WELDING 179

mined with regard to the convenience of the workman
and speed of handling the work after being brought
to a welding temperature. Unnatural positions at
the anvil should be avoided as good work is most
difficult of performance under these conditions.

Scarfing. — While there are many forms of welds,
depending on the relative shape of the pieces to be
joined, the portions that are to meet and form one
piece are always shaped in the same general way,
this shape being called a ' ' scarf. " The end of a
piece of work, when scarfed, is tapered off on one
side so that the extremity comes to a rather sharp
edge. The other side of the piece is left flat and a

Figure 50. — Scarfing Ends of Work Ready for Welding

continuation in the same straight plane with its side
of the whole piece of work. The end is then in the
form of a bevel or mitre joint (Figure 50).

Scarfing may be produced in any one of several
ways. The usual method is to bring the ends to a
forging heat, at which time they are upset to give
a larger body of metal at the ends to be joined. This
body of metal is then hammered down to the taper
on one side, the length of the tapered portion being
about one and a half times the thickness of the whole
piece being handled. Each piece should be given
this shape before proceeding farther.

The scarf may be produced by filing, sawing or
chiseling the ends, although this is not good practice
because it is then impossible to give the desired upset
and additional metal for the weld. This added thick-

180 WELDING

ness is called for by the fact that the metal burns
away to a certain extent or turns to scale, which is
removed before welding.

When the two ends have been given this shape
they should not fit as closely together as might be
expected, but should touch only at the center of the
area to be joined (Figure 51). That is to say, the
surface of the beveled portion should bulge in the
middle or should be convex in shape so that the edges
are separated by a little distance when the pieces are
laid together with the bevels toward each othefr.
This is done so that the scale which is formed on the

Figure 51. — Proper Shape of Scarfed Ends

metal by the heat of the fire can have a chance to
escape from the interior of the weld as the two parts
are forced together.

If the scarf were to be formed with one or more
of the edges touching each other at the same time
or before the centers did so, the scale would be im-
prisoned within the body of the weld and would cause
the finished work to be weak, while possibly giving
a satisfactory appearance from the outside.

Fluxes. — In order to assist in removing the scale
and other impurities and to make the welding sur-
faces as clean as possible while being joined, various
fluxing materials are used as in other methods of
welding.

For welding iron, a flux of white sand is usually
used, this material being placed on the metal after
it has been brought to a red heat in the fire. Steel

HAND FORGING AND WELDING 181

is welded with dry borax powder, this flux being
applied at the same time as the iron flux just men-
tioned. Borax may also be used for iron welding
and a mixture of borax with steel borings may also
be used for either class of work. Mixtures of sal
ammoniac with borax have been successfully used,
the proportions being about four parts of borax to
one of sal ammoniac. Various prepared fluxing
powders are on the market for this work, practically
all of them producing satisfactory results.

After the metal has been in the fire long enough
to reach a red heat, it is removed temporarily and,
if small enough -in size, the ends are dipped into a
box of flux. If the pieces are large, they may simply
be pulled to the edge of the fire and the flux then
sprinkled on the portions to be joined. A greater
quantity of flux is required in forge welding than
in electric or oxy-acetylene processes because of the
losses in the fire. After the powder has been applied
to the surfaces, the work is returned to the fire and
heated to the welding temperature.

Heating the Work. — After being scarfed, the two
pieces to be welded are placed in the fire and brought
to the correct temperature. This temperature can
only be recognized by experiment and experience.
The metal must be just below that pomt at which
small sparks begin to be thrown out of the fire and
naturally this is a hard point to distinguish. At the
welding heat the metal is almost ready to flow and is
about the consistency of putty. Against the back-
ground of the fire and coal the color appears to be
a cream or very light yellow and the work feels soft
as it is handled.

It is absolutely necessary that both parts be heated

182 WELDING

uniformly and so that they reach the welding tern-*
perature at the same time. For this reason they
should be as close together in the fire as possible and
side by side. When removed to be hammered to-
gether, time is saved if they are picked up in such
a way that when laid together naturally the beveled
surfaces come together. This makes it necessary that
the workman remember whether the scarfed side is
up or down, and to assist in this it is a good thing
to mark the scarfed side with chalk or in some other
noticeable manner, so that no mistake will be made
in the hurry of placing the work on the anvil.

The common practice in heating allows the tem-
perature to rise until the small white sparks are seen
to come from the fire. Any heating above this point
will surely result in burning that will ruin the iron
or steel being handled. The best welding heat can
be discerned by the appearance of the metal and
its color after experience has been gained with this
particular material. Test welds can be made and
then broken, if possible, so that the strength gained
through different degrees of heat can be known
before attempting more important work.

Welding. — When the work has reached the welding
temperature after having been replaced in the fire
with the flux applied, the two parts are quickly
tapped to remove the loose scale from their surfaces.
They are then immediately laid across the top of the
anvil, being placed in a diagonal position if both
pieces are straight. The lower piece is rested on the
anvil first with the scarf turned up and ready to
receive the top piece in the position desired. The
second piece must be laid in exactly the position it
is to finally occupy because the two parts will stick

HAND FORGING AND WELDING 183

together as soon as they touch and they cannot well
be moved after having once been allowed to come in
contact with each other. This part of the work must
be done without any unnecessary loss of time because
the comparatively low heat at which the parts weld
allows them to cool below the working temperature
in a few seconds.

The greatest difficulty will be experienced in with-
drawing the metal from the fire before it becomes
burned and in getting it joined before it cools below
this critical point. The beveled edges of the scarf
are, of course, the first parts to cool and the weld
must be made before they reach a point at which they
will not join, or else the work will be defective in
appearance and in fact.

If the parts being handled are of such a shape that
there is danger of bending a portion back of the
weld, this part may be cooled by quickly dipping it
into water before laying the work on the anvil to
be joined. ,

The workman uses a heavy hand hammer in making
the joint, and his helper, if one is employed, uses a
sledge. With the two parts of the work in place
on the anvil, the workman strikes several light blows,
the first ones being at a point directly over the center
of the weld, so that the joint will start from this
point and be worked toward the edges. After the
pieces have united the helper strikes alternate blows
with his sledge, always striking in exactly the same
place as the last stroke of the workman. The hammer
blows are carried nearer and nearer to the edges of
the weld and are made steadily heavier as the work
progresses.

The aim during the first part of the operation

184 WELDING

should be to make a perfect joint, with every part
of the surfaces united, and too much attention should
not be paid to appearance, at least not enough to
take any chance with the strength of the work.

It will be found, after completion of the weld, that
there has been a loss in length equal to one-half the
thickness of the metal being welded. This loss is
occasioned by the burned metal and the scale which
has been formed.

Finishing the Weld. — If it is possible to do so, the
material should be hammered into the shape that it
should remain with the same heat that was used for

Figure 52. — Upsetting and Scarfing the End of a Rod

welding. It will usually be found, however, that the
metal has cooled below the point at which it can be
worked to advantage. It should then be replaced in
the fire and brought back to a forging heat.

While shaping the work at this forging heat every
part that has been at a red heat should be ham-
mered with uniformly light and even blows as it cools.
This restores the grain and strength of the iron or
steel to a great extent and makes the unavoidable
weakness as small as possible.

Forms of Welds. — The simplest of all welds is that
called a "lap weld." This is made between the ends
of two pieces of equal size and similar form by
scarfing them as described and then laying one on
top of the other while they are hammered together.

A butt weld (Figure 52) is made between the ends

HAND FORGING AND WELDING 185

of two pieces of shaft or other bar shapes by upsetting
the ends so that they have a considerable' flare and
shaping the face of the end so that it is slightly
higher in the center than around the edges, this being
done to make the centers come together first. The
pieces are heated and pushed into contact, after which
the hammering is done as with any other weld.

A form similar to the butt weld in some ways is
used for joining the end of a bar to a flat surface
and is called a jump weld. The bar is shaped in
the same way as for a butt weld. The flat plate

Figure 53. — Scarfing for a T Weld

may be left as it is, but if possible a depression
should be made at the point where the shaft is to
be placed. With the two parts heated as usual, the
bar is dropped into position and hammered from
above. As soon as the center of the weld has been
made perfect, the joint may be finished with a fuller
driven all the way around the edge of the joint.

When it is required to join a bar to another bar
or to the edge of any piece at right angles the work
is called a "T" weld from its shape when complete
(Figure 53). The end of the bar is scarfed as
described and the point of the other bar or piece
where the weld is to be made is hammered so that it
tapers to a thin edge like one-half of a circular

186 WELDING

depression. The pieces are then laid together and
hammered as for a lap weld.

The ends of heavy bar shapes are often joined
with a "V," or cleft, weld. One bar end is shaped
so that it is tapering on both sides and comes to a
broad edge like the end of a chisel. The other bar
is heated to a forging temperature and then slit open
in a lengthwise direction so that the V-shaped open-
ing which is formed will just receive the pointed edge
of the first piece. With the work at welding heat,
the two parts are driven together by hammering on
the rear ends and the hammering then continues as

7

Figure 54. — Splitting Ends to Be Welded in Thin Work

with a lap weld, except that the work is turned over
to complete both sides of the joint.

The forms so far described all require that the
pieces be laid together in the proper position after
removal from the fire, and this always causes a slight
loss of time and a consequent lowering of the tem-
perature. With very light stock, this fall of tem-
perature would be so rapid that the weld would be
unsuccessful, and in this case the "lock" weld is
resorted to. The ends of the two pieces to be joined
are split for some distance back, and one-half of each
end is bent up and the other half down (Figure 54).
The two are then pushed together and placed in the
fire in this position. When the welding heat is
reached, it is only necessary to take the work out of
the fire and hammer the parts together, inasmuch as
they are already in the correct position.

HAND FORGING AND WELDING 187

Other forms of welds in which the parts are too
small to retain their heat, can be made by first
riveting them together or cutting them so that they
can be temporarily fastened in any convenient way
when first placed in the fire.

CHAPTER VIII

SOLDERING, BRAZING AND THERMIT WELDING
SOLDERING

Common solder is an alloy of one-half lead with
one-half tin, and is called "half and half." Hard
solder is made with two-thirds tin and one-third lead.
These alloys, when heated, are used to join surfaces
of the same or dissimilar metals such as copper, brass,
lead, galvanized iron, zinc, tinned plate, etc. These
metals are easily joined, but the action of solder with
iron, steel and aluminum is not so satisfactory and
requires greater care and skill.

The solder is caused to make a perfect union with
the surfaces treated with the help of heat from a
soldering iron. The soldering iron is made from a
piece of copper, pointed at one end and with the
other end attached to an iron rod and wooden handle.
A flux is used to remove impurities from the joint
and allow the solder to secure a firm union with the
metal surface. The iron, and in many cases the work,
is heated with a gasoline blow torch, a small gas
furnace, an electric heater or an acetylene and air
torch.

The gasoline torch which is most commonly used
should be filled two-thirds full of gasoline through
the hole in the bottom, which is closed by a screw
plug. After working the small hand pump for 10
to 20 strokes, hold the palm of your hand over the
end of the large iron tube on top of the torch and
open the gasoline needle valve about a half turn.
Hold the torch so that the liquid runs down into

188

SOLDERING, BRAZING AND THERMIT WELDING 189

the cup below the tube and fills it. Shut the gasoline
needle valve, wipe the hands dry, and set fire to
the fuel in the cup. Just as the gasoline fire goes
out, open the gasoline needle valve about a half turn
and hold a lighted match at the end of the iron tube
to ignite the mixture of vaporized gasoline and air.
Open or close the needle valve to secure a flame about
4 inches long.

On top of the iron tube from which the flame issues
there is a rest for supporting the soldering iron with
the copper part in the flame. Place the iron in the
flame and allow it to remain until the copper becomes
very hot, not quite red, but almost so.

A new soldering iron or one that has been misused
will have to be " tinned " before using. To do this,
take the iron from the fire while very hot and rub
the tip on some flux or dip it into soldering acid.
Then rub the tip of the iron on a stick of solder or
rub the solder on the iron. If the solder melts off the
stick without coating the end of the iron, allow a
few drops to fall on a piece of tin plate, then rub
the end of the iron on the tin plate with considerable
force. Alternately rub the iron on the solder and
dip into flux until the tip has a coating of bright
solder for about half an inch from the end. If the
iron is in very bad shape, it may be necessary to
scrape or file the end before dipping in the flux for
the first time. After the end of the iron is tinned
in this way, replace it on the rest of the torch so that
the tinned point is not directly in the flame, turning
the flame down to accomplish this.

Flux. — The commonest flux, which is called "sol-
dering acid," is made by placing pieces of zinc in
muriatic (hydrochloric) acid contained in a heavy

190 WELDING

glass or porcelain dish. There will be bubbles and
considerable heat evolved and zinc should be added
until this action ceases and the zinc remains in the
liquid, which is now chloride of zinc.

This soldering acid may be used on any metal to
be soldered by applying with a brush or swab. For
electrical work, this acid should be made neutral by
the addition of one part ammonia and one part water
to each three parts of the acid. This neutralized flux
will not corrode metal as will the ordinary acid.

Powdered resin makes a good flux for lead, tin
plate, galvanized iron and aluminum. Tallow, olive
oil, beeswax and vaseline are also used for this pur-
pose. Muriatic acid may be used for zinc or gal-
vanized iron without the addition of the zinc, as de-
scribed in making zinc chloride. The addition of
two heaping teaspoonfuls of sal ammoniac to each
pint of the chloride of zinc is sometimes found to-
improve its action.

Soldering Metal Parts. — All surfaces to be joined
should be fitted to each other as accurately as pos-
sible and then thoroughly cleaned with a file, emery
cloth, scratch bush or by dipping in lye. "Work may
be cleaned by dipping it into nitric acid which has
been diluted with an equal volume of water. The
work should be heated as hot as possible without
danger of melting, as this causes the solder to flow
better and secure a much better hold on the surfaces.
Hard solder gives better results than half and half,
but is more difficult to work. It is very important
that the soldering iron be kept at a high heat during
all work, otherwise the solder will only stick to the
surfaces and will not join with them.

Sweating is a form of soldering in which the sur-

SOLDERING, BRAZING AND THERMIT WELDING 191

faces of the work are first covered with a thin layer
of solder by rubbing them with the hot iron after
it has been dipped in or touched to the soldering
stick. These surfaces are then placed in contact
and heated to' a point at which the solder melts and
unites. Sweating is much to be preferred to ordinary
soldering where the form of the work permits it.
This is the only method which should ever be used
when a fitting is to be placed over the end of a length
of tube.

Soldering Holes. — Clean the surfaces for some dis-
tance around the hole until they are bright, and apply
flux while holding the hot iron near the hole. Touch
the tip of the iron to some solder until the solder is
picked up on the iron, and then place this solder,
which was just picked up, around the edge of the
hole. It will leave the soldering iron and stick to
the metal. Keep adding solder in this way until the
hole has been closed up by working from the edges
and building toward the center. After the hole is
closed, apply more flux to the job and smooth over
with the hot iron until there are no rough spots.
Should the solder refuse to flow smoothly, the iron
is not hot enough.

Soldering Seams. — Clean back from the seam or
split for at least half an inch all around and then
build up the solder in the same way as was done writh
the hole. After closing the opening, apply more flux
to the work and run the hot iron lengthwise to
smooth the job.

Soldering Wires. — Clean all insulation from the
ends to be soldered and scrape the ends bright. Lay
the ends parallel to each other and, starting at the
middle of the cleaned portion, wrap the ends around

192

each other, one being wrapped to the right, the other
to the left. Hold the hot iron under the twisted joint
and apply flux to the wire. Then dip the iron in
the solder and apply to the twisted portion until
the spaces between the wires are filled with solder.
Finish by smoothing* the joint and cleaning away
all excess metal by rubbing the hot iron lengthwise.
The joint should now be covered with a layer of
rubber tape and this covered with a layer of ordinary
friction tape.

Steel and Iron. — Steel surfaces should be cleaned,
then covered with clear muriatic acid. "While the
acid is on the metal, rub with a stick of zinc and then
tin the surfaces with the hot iron as directed. Cast
iron should be cleaned and dipped in strong lye to
remove grease. Wash the lye away with clean water
and cover with muriatic acid as with steel. Then
rub with a piece of zinc and tin the surfaces by
using resin as a flux.

It is very difficult to solder aluminum with ordi-
nary solder. A special aluminum solder should be
secured, which is easily applied and makes a strong
joint. Zinc or phosphor tin may be used in place
of ordinary solder to tin the surfaces or to fill small
holes or cracks. The aluminum must be thoroughly
heated before attempting to solder and the flux may
be either resin or soldering acid. The aluminum must
be thoroughly cleaned with dilute nitric acid and
kept hot while the solder is applied by forcible rub-
bing with the hot iron.

BRAZING

This is a process for joining metal parts, very
similar to soldering, except that brass is used to

SOLDERING, BRAZING AND THERMIT WELDING 193

make the joint in place of the lead and zinc alloys
which form solder. Brazing must not be attempted
on metals whose melting point is less than that of
sheet brass.

Two pieces of brass to be brazed together are heated
to a temperature at which the brass used in the process
will melt and flow between the surfaces. The brass
amalgamates with the surfaces and makes a very
strong and perfect joint, which is far superior to
any form of soldering where the work allows this
process to be used, and in many cases is the equal of
welding for the particular field in which it applies.

Brazing Heat and Tools. — The metal commonly
used for brazing will melt at heats between 1350°
and 1650° Fahrenheit. To bring the parts to this
temperature, various methods are in use, using solid,
liquid or gaseous fuels. While brazing may be ac-
complished with the fire of the blacksmith forge, this
method is seldom satisfactory because of the difficulty
of making a sufficiently clean fire with smithing coal,
and it should not be used when anything else is
available. Large jobs of brazing may be handled
with a charcoal fire built in the forge, as this fuel
produces a very satisfactory and clean fire. The
only objection is in the difficulty of confining the
heat to the desired parts of the work.

The most satisfactory fire is that from a fuel gas
torch built for this work. These torches are simply
forms of Bunsen burners, mixing the proper quan-
tity of air with the gas to bring about a perfect
combustion. Hose lines lead to the mixing tube of
the gas torch, one line carrying the gas and the other
air under a moderate pressure. The air line is often
dispensed with, allowing the gas to draw air into the

194 WELDING

burner on the injector principle, much the same as
with illuminating gas burners for use with incan-
descent mantles. Valves are provided with which
the operator may regulate the amount of both gas
and air, and ordinarily the quality and intensity
of the flame.

When gas is not available, recourse may be had
to the gasoline torch made for brazing. This torch
is built in the same way as the small portable gasoline
torches for soldering operations, with the exception
that two regulating needle valves are incorporated
in place of only one.

The torches are carried on a framework, which also
supports the work being handled. Fuel is forced
to the torch from a large tank of gasoline into which
air pressure is pumped by hand. The torches are
regulated to give the desired flame by means of the
needle valves in much the same way as with any
other form of pressure torch using liquid fuel.

Another very satisfactory form of torch for brazing
is the acetylene-air combination described in the
chapter on welding instruments. This torch gives
the correct degree of heat and may be regulated to
give a clean and easily controlled flame.

Regardless of the source of heat, the fire or flame
must be adjusted so that no soot is deposited on the
metal surfaces of the work. This can only be accom-
plished by supplying the exact amounts of gas and
air that will produce a complete burning of the fuel.
With the brazing torches in common use two heads
are furnished, being supplied from the same source
of fuel, but with separate regulating devices, The
torches are adjustably mounted in such a way that
the flames may be directed toward each other, heat-

SOLDERING, BRAZING AND THERMIT WELDING 19£

ing two sides of the work at the same time and allow-
ing the pieces to be completely surrounded with the
flame.

Except for the source of heat, tut one tool is
required for ordinary brazing operations, this being
a spatula formed by flattening one end of a quarter-
inch steel rod. The spatula is used for placing the
brazing metal on the work and for handling the flux
that is required in this work as in all other similar
operations.

Spelter. — The metal that is melted into the joint is
called spelter. While this name originally applied
to but one particular grade or composition of metal,
common use has extended the meaning until it is
generally applied to all grades.

Spelter is variously composed of alloys containing
copper, zinc, tin and antimony, the mixture employed
depending on the work to be done. The different
grades are of varying hardness, the harder kinds
melting at higher temperatures than the soft ones
and producing a stronger joint when used. The
reason for not using hard spelter in all cases is the
increased difficulty of working it and the fact that
its melting point is so near to some of the metals
brazed that there is great danger of melting the work
as well as the spelter.

The hardest grade of spelter is made from three-
fourths copper with one-fourth zinc and is used for
working on malleable and cast iron and for steel.
This hard spelter melts at about 1650° and is cor-
respondingly difficult to handle.

A spelter suitable for working with copper is made
from equal parts of copper and zinc, melting at about
1400° Fahrenheit, 500° below the melting point of

196 WELDING

the copper itself. A still softer brazing metal is
composed of half copper, three-eighths zinc and one-
eighth tin. This grade is used for fastening brass to
iron and copper and for working with large pieces of
brass " to brass. For brazing thin sheet brass and
light brass castings, a metal is used which contains
two-thirds tin and one-third .antimony. The low
melting point of this last composition makes it very
easy to work with and the danger of melting the
work is very slight. However, as might be expected,
a comparatively weak joint is secured, which will not
stand any great strain.

All of the above brazing metals are used in powrder
form so that they may be applied with the spatula
where the joint is exposed on the outside of the
work. In case it is necessary to braze on the inside
of a tube or any deep recess, the spelter may be
placed on a flat rod long enough to reach to the
farthest point. By distributing the spelter at the
proper points along the rod it may be placed at the
right points by turning the rod over after inserting
into the recess.

Flux. — In order to remove the oxides produced
under brazing heat and to allow the brazing metal to
flow freely into place, a flux of some kind must be
used. The commonest flux is simply a pure calcined
borax powder, that is, a borax powder that has been
heated until practically all the water has been driven
off.

Calcined borax may also be mixed with about 15
per cent of sal ammoniac to make a satisfactory
fluxing powder. It is absolutely necessary to use-
flux of some kind and a part of whatever is used
should be made into a paste with water so that it

SOLDERING, BRAZING AND THERMIT WELDING 197

can be applied to the joint to be brazed before heat-
ing. The remainder of the powder should be kept
dry for use during the operation and after the heat
has been applied.

Preparing the Work. — The surfaces to be brazed
are first thoroughly cleaned with files, emery cloth or
sand paper. If the work is greasy, it should be
dipped into a bath of lye or hot soda water so that
all trace of oil is removed. The parts are then placed
in the relation to each other that they are to occupy
when the work has been completed. The edges to
be joined should make a secure and tight fit, and
should match each other at all points so that the
smallest possible space is left between them. This
fit should not be so tight that it is necessary to force
the work into place, neither should it be loose enough
to allow any considerable space between the surfaces.
The molten spelter will penetrate between surfaces
that water will flow between when the work and spelter
have both been brought to the proper heat. It is, of
course, necessary that the two parts have a sufficient
number of points of contact so that they will remain
in the proper relative position.

The work is placed on the surface of the brazing
table in such a position that the flame from the
torches will strike the parts to be heated, and with
the joint in such a position that the melted spelter
will flow down through it and fill every possible part
of the space between the surfaces under the action
of gravity. That means that the edge of the joint
must be uppermost and the crack to be filled must
not lie horizontal, but at the greatest slant possible.
Better than any degree of slant would be to have
the line of the joint vertical.

198 WELDING

The work is braced up or clamped in the proper
position before commencing to braze, and it is best
to place fire brick in such positions that it will be
impossible for cooling draughts of air to reach the
heated metal should the flame be removed temporarily
during the process. In case there is a large body of
iron, steel or copper to be handled, it is often advis-
able to place charcoal around the work, igniting this
with the flame of the torch before starting to braze
so that the metal will be maintained at the correct
heat without depending entirely on the torch.

"When handling brass pieces having thin sections
there is danger of melting the brass and causing it
to flow away from under the flame, with the result
that the work is ruined. If, in the judgment of the
workman, this may happen with the particular job
in hand, it is well to build up a mould of fire clay
back of the thin parts or preferably back of the
whole piece, so that the metal will have the necessary
support. This mould may be made by mixing the
fire clay into a stiff paste with water and then packing
it against the piece to be supported tightly enough
so that the form will be retained even if the metal
softens.

Brazing. — With the work in place, it should be wrell
covered with the paste of flux and water, then heated
until this flux boils up and runs over the surfaces.
Spelter is then placed in such a position that it will
run into the joint and the heat is continued or
increased until the spelter melts and flows in between
the two surfaces. The flame should surround the
work during the heating so that outside air is ex-
cluded as far as is possible to prevent excessive
oxidization.

SOLDERING, BRAZING AND THERMIT WELDING 199

When handling brass or copper, the flame should
not be directed so that its center strikes the metal
squarely, but so that it glances from one side or the
other. Directing the flame straight against the work
is often the cause of melting the pieces before the
operation is completed. When brazing two different
metals, the flame should play only on the one that
melts at the higher temperature, the lower melting
part receiving its heat from the other. This avoids
the danger of melting one before the other reaches
the brazing point.

The heat should be continued only long enough io
cause the spelter to flow into place and no longer.
Prolonged heating of any metal can do nothing but
oxidize and weaken it, and this practice should be
avoided as much as possible. If the spelter melts into
small globules in place of flowing, it may be caused
to spread and run into the joint by lightly tapping
the work. More dry flux may be added with the
spatula if the tapping does not produce the desired
result.

Excessive use of flux, especially toward the end
of the work, will result in a very hard surface on
all the work, a surface which will be extremely diffi-
cult to finish properly. This trouble will be present
to a certain extent anyway, but it may be lessened
by a vigorous scraping with a wire brush just as
soon as the work is removed from the fire. If allowed
to cool before cleaning, the final appearance will not
be as good as with the surplus metal and scale re-
moved immediately upon completing the job.

After the work has been cleaned with the brush
it may be allowed to cool and finished to the desired
shape, size and surface by filing and polishing. When

200 WELDING

filed, a very thin line of brass should appear where
the crack was at the beginning of the work. If it
is desired to avoid a square shoulder and fill in an
angle joint to make it rounding, the filling is best
accomplished by winding a coil of very thin brass
wire around the part of the work that projects and
then causing this to flow itself or else allow the spelter
to fill the spaces between the layers of wire. Copper
wire may also be used for this purpose, the spaces
being filled with melted spelter.

THERMIT WELDING

The process of welding which makes use of the
great heat produced by oxygen combining with alumi-
num is known as the Thermit process and was per-
fected by Dr. Hans Goldschmidt. The process, which
is controlled by the Goldschmidt Thermit Company,
makes use of a mixture of finely powdered aluminum
with an oxide of iron called by the trade name,
Thermit.

The reaction is started with a special ignition
powder, such as barium superoxide and aluminum,
and the oxygen from the iron oxide combining with
the aluminum, producing a mass of superheated steel
at about 5000 degrees Fahrenheit. After the reac-
tion, which takes from 30 seconds to a minute, the
molten metal is drawn from the crucible on to the
surfaces to be joined. Its extreme heat fuses the
metal and a perfect joint is the result. This process
is suited for welding iron or steel parts of compara-
tively large size.

Preparation. — The parts to be joined are thoroughly
cleaned on the surfaces and. for several inches back
from the joint, after which they are supported in

SOLDERING, TRAZING AND THERMIT WELDING 201

place. The surfaces between which the met^l will
flow are separated from % to 1 inch, depending on
the size of the parts, but cutting or drilling part of
the metal away. After this separation is made for
allowing the entrance of new metal, the effects of
contraction of the molten steel are cared for by pre-
heating adjacent parts or by forcing the ends apart
with wedges and jacks. The amount of this last
separation must be determined by the shape and
proportions of the parts in the same way as would
be done for any other class of welding which heats
the parts to a melting point.

Yellow wax, which has been warmed until plastic,
is then placed around the joint to form a collar, the
wax completely filling the space between the ends
and being provided with vent holes by imbedding a
piece of stout cord, which is pulled out after the
wax cools.

A retaining mould (Figure 55) made from sheet
steel or fire brick is then placed around the parts.
This mould is then filled with -a mixture of one part
fire clay, one part ground fire brick and one part
fire sand. These materials are well mixed and
moistened with enough water so that they will pack.
This mixture is then placed in the mould, filling the
space between the walls and the wax, and is packed
hard with, a rammer so that the material forms a
wall several inches thick between any point of the
mould and the wax. The mixture must be placed
in the mould in small quantities and packed tight
as the filling progresses.

Three or more openings are provided through this
moulding material by the insertion of wood or pipe
forms. One of these openings will lead from the

202

WELDING

SOLDERING, BRAZING AND THERMIT WELDING 203

lowest point of the wax pattern and is used for the
introduction of the preheating flame. Another open-
ing leads from the top of the mould into this pre-
heating gate, opening into the preheating gate at a
point about one inch from the wax pattern. Open-
ings, called risers, are then provided from each of
the high points of the wax pattern to the top of the
mould, these risers ending at the top in a shallow
basin. The molten metal comes up into these risers
and cares for contraction of the casting, as well as
avoiding defects in the collar of the weld. After
the moulding material is well packed, these gate
patterns are tapped lightly and withdrawn, except
in the case of the metal pipes which are placed at
points at which it would be impossible to withdraw
a pattern.

Preheating. — The ends to be welded are brought
to a bright red heat by introducing the flame from
a torch through the preheating gate. The torch must
use either gasoline or kerosene, and not crude oil, as
the crude oil deposits too much carbon on the parts.
Preheating of other adjacent parts to care for con-
traction is done at this time by an additional torch
burner.

The heating flame is started gently at first and
gradually increased. The wax will melt and may
be allowed to run out of the preheating gate by
removing the flame at intervals for a few seconds.
The heat is continued until the mould is thoroughly
dried and the parts to be joined are brought to the
red heat required. This leaves a mould just the shape
of the wax pattern.

The heating gate should then be plugged with a
sand core, iron plug or piece of fitted fire brick, and

204

WELDING

backed up with several shovels full of the moulding
mixture, well packed.

Thermit Metal. — The reaction takes place in a spe-
cial crucible lined with magnesia tar, which is baked
at a red heat until the tar is driven off and the
magnesia left. This lining should last from twelve

Figure 56. — Thermit Crucible Plug. A, Hard burnt magnesia
stone ; B, Magnesia thimble ; C, Refractory sand ; D, Metal disc ; E,
Asbestos washer ; F, Tapping pin

to fifteen reactions. This magnesia lining ends at
the bottom of the crucible in a ring of magnesia stone
and this ring carries a magnesia thimble through
which the molten steel passes on its way to the mould.
It will usually be necessary to renew this thimble
after each reaction. This lower opening is closed
before filling the crucible with thermit by means of
a small disc or iron carrying a stem, which is called
a tapping pin (Figure 56). This pin, F, is placed

SOLDERING, BRAZING AND THERMIT WELDING 205

in the thimble with the stem extending down
through the opening and exposing about two inches.
The top of this pin is covered with an asbestos,
washer, E, then with another iron disc, D, and finally
with a layer of refractory sand. The crucible is tapped
by knocking the stem of the pin upwards with a
spade or piece of flat iron about four feet long.

The charge of thermit is added by placing a few
handfuls over the refractory sand and then pouring
in the balance required. The amount of thermit re-
quired is calculated from the wax used. The wrax is
weighed before and after filling the entire space that
the thermit will occupy. This does not mean only
the wax collar, but the space of the mould with all
gates filled with wax. The number of pounds of
wax required for this filling multiplied by 25 will
give the number of pounds of thermit to be used.
To this quantity of thermit should be added 1 per
cent of pure manganese, 1 per cent nickel thermit and
15 per cent of steel punchings.

It is necessary, when more than 10 pounds of
thermit will be used, to mix steel punchings not
exceeding % inch diameter by % inch thick with
the powder in order to sufficiently retard the inten-
sity of the reaction.

Half a teaspoonful of ignition powder is placed
on top of the thermit charge and ignited with a
storm match or piece of red hot iron. The cover
should be immediately closed on the top of the
cru-cible and the operator should get away to a safe
distance because of the metal that may be thrown
out of the crucible.

After allowing about 30 seconds to a minute for
the reaction to take place and the slag to rise to the

206 WELDING

top of the ciueible, the tapping pin is struck from
below and the molten metal allowed to run into the
mould. The mould should be allowed to remain in
place as long as possible, preferably over night, so
as to anneal the steel in the weld, but in no case
should it be disturbed for several hours after pouring.
After removing the mould, drill through the metal
left in the riser and gates and knock these sections
off. No part of the collar should be removed unless
absolutely necessary.

CHAPTER IX
OXYGEN PROCESS FOB REMOVAL OF CARBON

Until recently the methods used for removing car-
bon deposits from gas engine cylinders were very im-
practical and unsatisfactory. The job meant dis-
mantling the motor, tearing out all parts, and scraping
the pistons and cylinder walls by hand.

The work was never done thoroughly. It required
hours of time to do it, and then there was always the
danger of injuring the inside of the cylinders.

These methods have been to a large extent super-
seded by the use of oxygen under pressure. The
various devices that are being manufactured are
known as carbon removers, decarbonizers, etc., and
large numbers of them are in use in the automobile
and gasoline traction motor industry.

Outfit. — The oxygen carbon cleaner consists of a
high pressure oxygen cylinder with automatic reduc-
ing valve, usually constructed on the diaphragm prin-
ciple, thus assuring positive regulation of pressure.
This valve is fitted with a pressure gauge, rubber hose,
decarbonizing torch with shut off and flexible tube for
insertion into the chamber from which the carbon is to
be removed.

There should also be an asbestos swab for swabbing
out the inside of the cylinder or other chamber with
kerosene previous to starting the operation. The
action consists in simply burning the carbon to a fine
dust in the presence of the stream of oxygen, this dust
being then blown out.

207

208 WELDING

Operation. — The following are instructions for oper-
ating the cleaner : —

(1) Close valve in gasoline supply -line and start
the motor, letting it run until the gasoline is ex-
hausted.

(2) If the cylinders be T or L head, remove either
the inlet or the exhaust valve cap, or a spark plug if
the cap is tight. If the cylinders have overhead valves,
remove a spark plug. If any spark plug is then re-
maining in the cylinder it should be removed and an
old one or an iron pipe plug substituted.

(3) Raise the piston of the cylinder first to be
cleaned to the top of the compression stroke and con-
tinue this from cylinder to cylinder as the work pro-
gresses.

(4) In motors where carbon has been burned hard,
the cylinder interior should then be swabbed with
kerosene before proceeding. Work the swab, saturated
with kerosene, around the inside of the cylinder until
all the carbon has been moistened with the oil. This
same swab may be used to ignite the gas in the cyl-
inder in place of using a match or taper.

(5) Make all connections to the oxygen cylinder.

(6) Insert the torch nozzle in the cylinder, open the
torch valve gradually and regulate to about two Ibs.
pressure. Manipulate the nozzle inside the cylinder
and light a match or other flame at the opening so
that the carbon starts to burn. Cover the various
points within the cylinder and when there is no
further burning the carbon has been removed. The
regulating and oxygen tank valves are operated in
exactly the same way as for welding as previously
explained.

It should be carefully noted that when the piston is

OXYGEN PROCESS FOR REMOVAL OF CARBON 209

up, ready to start the operation, both valves must be
closed. There will be a considerable display of sparks
while this operation is taking place, but they will not
set fire to the grease and oil. Care should be used to
see that no gasoline is about.

INDEX

PAGE

Acetylene 42

filtering 78

generators 60

in tanks 49

piping 79

properties of 46

purification of 47

Acetylene-air torches 104

Air 36

oxygen from 35

Alloys 11, 20

table of 137

Alloy steel 15

Aluminum 17

alloys 24

welding 130

Annealing 27

Anvil 172

Arc welding, electric 160

machines . . . . : 166

Asbestos, use of, in welding 58

Babbitt 24

Bending pipes and tubes 176

Bessemer steel 16

Beveling 115, 116

Brass 22

welding 132

Brazing 155, 188, 192, 198

electric 155

heat and tools 193

spelter 195

Bronze 23

welding 132

Butt welding 151

211

212 INDEX

PAGE

Calcium carbide 43

Carbide 43

storage of, Fire Underwriters ' Eules 45

to water generator 64

Carbon removal 33

by oxygen process 207

Case hardening steel 32

Cast iron 12

welding 150

Champf ering 113

Charging generator 69

Chlorate of potash oxygen 41

Conductivity of metals 140

Copper 18

alloys 22

welding 131

Crucible steel 16

Cutting, oxy-acetylene 33

torches 103

Dissolved acetylene 50

Electric arc welding 160

Electric welding 142

troubles and remedies 155

Expansion of metals 141

Flame, welding 121

Fluxes 54, 180

for brazing 196

for soldering 189

Forge 170

fire 171

practice 173

tools 171

tuyere construction of 170

welding 182

welding preparation 178

welds, forms of 184

Forging 170

Gas holders 66, 77

Gases, heating power of 139

Generator, acetylene 60

carbide to water 64

construction 68

INDEX 213

Generator PAGE

location of 84

operation and care of 71

overheating 62

requirements 61

water to carbide 63

German silver 24

Gloves 56

Goggles 56

Hand forging 170

Hardening steel 27

Heat treatment of steel 25

Hildebrandt process 39

Hose 58

Injectors, adjuster 99

Iron 11

cast 12

grades of 14

malleable cast 13

wrought 13

Jump weld 185

Lap welding 154

Lead 18

Linde process 38

Liquid air oxygen 38

Magnalium 24

Malleable iron 13

welding 128

Melting points of metals 139

Metal alloys, table of 137

Metals •. 11

characteristics of 125

conductivity of 140

expansion of 141

heat treatment of 11

melting points of 139

tensile strength of 140

weight of 141

Nickel 20

Nozzle sizes, tore!1 102

214 INDEX

PAGE

Open hearth steel 17

Oxy-acetylene cutting 33

welding practice 106

Oxygen 35

cylinders 39

weight of 39

Pipes, bending 176

Platinum 20

Preheating 106, 203

[Removal of carbon by oxygen process 207

Eesistance method of electric welding 142

Eestoration of steel 132

Kods, welding 52

Safety devices 80

Scarfing 179

Solder 24

Soldering 188

flux 188

holes 191

seams 191

steel and iron 192

wires 191

Spelter 195

Spot welding 143, 154

Steel 14

alloys 15, 21

Bessemer 16

crucible 16

heat treatment of 25

open hearth 17

restoration of 132

tensile strength of 15

welding 150

Strength of metals 140

Tank valves 85

Tapering 114

Tables of welding information 136-141

Tempering steel 30

Thermit metal 204

preheating 203

preparation 200

welding 188, 200

INDEX 213

PAGE

Tin 19

Torch 90

acetylene-air 104

care 101

construction 100

cutting 103

high pressure 96

low pressure 98

medium pressure 97

nozzles 102

practice 34, 118

Valves, regulating 86

tank 85

Water 37

to carbide generator 63

Welding aluminum 130

brass 132

bronze 132

butt : 151

cast iron . . . . 127

copper 131

electric 142

electric arc 160

flame 121

forge 182

information and tables 135-141

instruments 85

lap 154

malleable iron 128

materials 33

practice, oxy-acetylene 106

rods 52

spot 143, 154

steel 129

table 57

thermit 188, 200

torches 90

various metals 125

wrought iron 129

Wrought iron 13

welding 129

Zinc . . 19

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