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Book for the experienced professional or first time welder. Every welder should to perfect their welding skills and knowlenge. Reveals welding secrets and tricks, to do simple metalworking on sheet metal or heavier stock. This work involves welding, or cutting. The equipment and the procedure for work are described in this manual. Some tips that will help you do a better, safer job in places that should be welded. Hope this book will help you be a better welder.
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Veröffentlichungsjahr: 2025
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Book title: A Welding Guide for Experienced Welder and Self Taught Welder by Vladimir Kharchenko
2024 Vladimir Kharchenko
All rights reserved.
Author: Vladimir Kharchenko
Podpolnaya, 69. Kherson. Ukraine 73000. [email protected]
ISBN: 9783689955069
A Welding Guide for Experienced Welder and Self Taught Welder.
BbookK
Book for the experienced professional or first time welder. Every welder should to perfect their welding skills and knowlenge. Reveals welding secrets and tricks, to do simple metalworking on sheet metal or heavier stock. This work involves welding, or cutting. The equipment and the procedure for work are described in this manual. Some tips that will help you do a better, safer job in places that should be welded. Hope this book will help you be a better welder.
INTRODUCTION
In this book I've tried to help those of you who will go on welding a long time after. I have seen a lot of welds in my life and is enough to convince me that some people still don't know where not to weld. Some tips that will help you do a better, safer job in places that should be welded. Hope this book will help you be a better welder. The information in it gathered the hard way over 49 years.
GAS WELDING AND CUTTING
General
Fusion welding is the process of joining metals by melting or fusing together adjacent surfaces or edges without applying pressure. The heat for fusing the metal may be provided either by gases or electricity. Fusion welding is an important function of every military automotive maintenance shop. By use of the Oxyacetylene process, iron and steel can be severed, shaped, or joined, and other metals can be joined. Permanent repairs can usually be made by welding, even in the field, avoiding the necessity for temporary or "stop-gap" repairs.
a. The gases commonly used for welding or cutting are oxygen and acetylene, although oxygen with some other fuel gas is sometimes used. This section describes the Oxyacetylene process. Electric welding will be described in section IV. Almost the same results can be accomplished by either process. The oxyacetylene outfit is somewhat more portable than the electric and is usually available even in mobile shops. The oxyacetylene process cuts steel and iron very efficiently.
b. An important use of the oxyacetylene process, especially in the small shop or in the field, is for heating. When forges and other blacksmithing equipment are not available, simple bending and forming operations can be performed easily by using the welding torch to heat the metal to forging temperature, or for annealing, hardening, and tempering operations, if necessary.
Safety precautions
Acetylene is an inflammable gas that is explosive when mixed with air. Oxygen is a chemically active gas. Both are compressed into cylinders under high pressures for industrial uses, and both are extremely dangerous unless the safety precautions mentioned throughout this section and in the manufacturers' literature are strictly observed. One of the most important of these is never to oil regulators, torches, or any part of welding or cutting apparatus and never let oil or grease come in contact with or be near oxygen. Oil or grease coming in contact with pure oxygen under pressure will ignite violently or explode.
Equipment
In its simplest form an oxyacetylene welding and cutting outfit consists of a cylinder of oxygen, a cylinder of acetylene, two regulators, two lengths of hose with fittings, and a welding torch supplemented by a cutting attachment or a separate cutting torch. With this equipment all commercial metals can be welded; steel, wrought iron or cast iron can be cut; and local metal heating operations can be done effectively. Mounted on a hand truck as shown in figure 33, such an outfit is portable and can be taken wherever the work is located. In addition, goggles are required to protect the welder's eyes, gloves to protect his hands, and a friction lighter to light the torch without danger of burning them. Wrenches are needed for cylinders, regulators, and torches. Welding rod or flux, or both, are also usually required. Interchangeable tips or heads of different sizes must be provided for the torches if the same handles are to be used for a variety of operations.
Acetylene
FIGURE 33.—Portable oxyacetylene welding outfit.
a. Acetylene is a fuel gas having a distinctive odor, composed of carbon and hydrogen, its chemical formula being C2H2. It is manufactured by the action of water on calcium carbide, a crushed, rock-like substance produced in an electric furnace from coke and limestone. The gas is contained in steel cylinders under a pressure of about 225 pounds per square inch when the cylinder is full. An acetylene cylinder is not hollow ; it is filled with a porous material saturated with acetone, a liquid chemical which absorbs many times its own volume of acetylene. The acetylene is dissolved in the acetone under pressure in the same way that carbon dioxide gas (CO2) is dissolved under pressure in a bottle of soda water. This treatment makes the acetylene safe, even under the high 225-pound pressure, and allows enough acetylene to be stored in a cylinder for several days' use under average conditions. The usual capacity of an acetylene cylinder is about 300 cubic feet. The cylinder itself is a strong steel container provided with a valve for attaching the regulator and drawing off the acetylene. Acetylene, once it has left the cylinder, is called "free." In this state it is liable to explode spontaneously when used at gage pressure over 15 pounds per square inch. A safety fuse plug which melts and releases the gas from the container is provided in case of fire. A cylinder of acetylene of 300 cubic feet capacity weighs 232.5 pounds full and 214 pounds empty. Smaller cylinders containing approximately 100 cubic feet are available. Empty cylinders must be returned to the manufacturer for recharging.
b. For safety's sake, remember that acetylene will burn- and will form explosive mixtures with air. Handle acetylene cylinders care fully and store them in a well-ventilated, dry place away from combustible materials, stoves, radiators, or furnaces. Keep the valve end up. Never tamper with fuse plugs.
Oxygen
a. Oxygen is a colorless, odorless, and tasteless gas. It is necessary for the combustion of most substances and combines chemically with them when they burn. Oxygen itself is not inflammable but is said to support combustion. For ordinary fires, such as forge and furnace fires, the oxygen in the air supports combustion of the fuel. Except for a very small percentage of rare gases, such as argon, neon, and helium, the atmosphere is composed of about one-fifth oxygen and four-fifths nitrogen. Nitrogen does not aid in combustion but merely cools off the fire. It can be seen, therefore, that the pure oxygen is a much more active agent than air in supporting combustion.
b. The bulk of the oxygen used in industry today is obtained from the atmosphere by the liquid air process ; a small amount is made from water by the electrolytic process. Air is liquefied by a process of compression, cooling, and expansion, and oxygen is separated from the resulting extremely cold liquid by fractional distillation, in which advantage is taken of the fact that liquid nitrogen boils at a lower temperature than liquid oxygen. The distilling apparatus delivers practically pure oxygen to a storage holder, from which it is com pressed into steel cylinders for distribution.
c. Oxygen is produced by the electrolytic process, as follows: Water is a chemical compound of hydrogen and oxygen (H2O), each of which is a gas in its uncombined state. Under suitable conditions, an electric current passed through water decomposes it into its two elements. Bubbles of oxygen rise from the positive electrical terminal or electrode and hydrogen bubbles from the negative electrode. Each gas is led to a storage holder and then compressed in cylinders.
d. Oxygen cylinders are very strong, seamless, drawn-steel containers into which the oxygen is compressed to the extremely high pressure of 2,000 pounds per square inch. This pressure is measured at 70° F. and becomes somewhat greater when the cylinder is at a higher temperature and somewhat less when it is at a lower temperature. The pressure decreases as the oxygen is drawn off and the cylinder emptied. Unlike acetylene cylinders, oxygen cylinders are hollow. They are provided with specially designed valves to resist the high pressure. Every oxygen cylinder valve has some kind of a safety device to blow off the oxygen in case the cylinder is directly exposed to fire. The usual oxygen cylinder contains 220 cubic feet of oxygen and is 56 inches in height (including valve) and 9 inches in diameter. It weighs about 148 pounds full and 130 pounds empty. Smaller cylinders containing 110 cubic feet are available. The cylinder must be returned to the manufacturer when empty.
e. Oxygen is not an inflammable gas but causes other burning materials to burn more violently when they are exposed to it. It will cause oily or greasy substances to burst into flame with explosive violence without any other ignition. Always remember this when using it. Never confuse oxygen with compressed air and never use it to supply head pressure on a tank. It would be fatal to put pressure on the tank of a kerosene preheating torch, for instance. Never use oxygen for pneumatic tools, to start internal combustion engines, to blow out pipe, or to "dust" clothes. Oxygen cylinders are strong enough to withstand ordinary handling, but they should not be dropped off platforms, knocked about, or placed where heavy articles may drop on them. Do not store them in hot places or where oil may drop on them from overhead bearings or machines.
Regulators
FIGURE 34. — Oxygen and acetylene regulators.
a. General. —The function of a regulator (fig. 34) is to reduce the high pressure of the gas in the cylinder to a low constant working pressure at the torch. For example, a cylinder contains oxygen at a pressure of 2,000 pounds per square inch, and a pres sure of only 10 pounds per square inch is wanted at the torch to do some welding. The regulator must reduce the cylinder pressure from 2,000 to 10 pounds per square inch and must maintain this working pressure as the cylinder pressure decreases. Therefore, a regulator must have a sensitive regulating mechanism in addition to a reducing valve.
(1) A regulator for either an acetylene or an oxygen container has a union nipple for attaching it to the cylinder and an outlet connection for the hose leading to the torch. There are two gages on the body of the regulator : one shows the pressure in the cylinder, and the other the working pressure being supplied to the torch. The working pres sure is adjusted by a hand screw. When this screw is turned to the left (counterclockwise) until it turns freely, the valve inside the regulator is closed and no gas can pass to the torch. Turning the handle to the right (clockwise) opens the valve, and gas passes to the torch at the pressure shown on the working pressure gage. The more the hand screw is turned to the right, the higher the pressure shown on the working pressure gage. Typical regulators are shown in figure 34.
(2) Before opening the valve on a cylinder to which a regulator is attached, the pressure-adjusting screw must be fully released by turning it to the left (counterclockwise) until it turns freely. Other wise, when the cylinder valve is opened, the valve and seat will be forced together by the full pressure of the gas, which, in the case of an oxygen cylinder, may be as high as 2,200 pounds per square inch. The impact would ruin the valve seat, and the regulator would be unsafe to use until repaired.
b. Construction. —The details of regulator construction vary with different manufacturers but the fundamentals of operation are the same in all. The basic differences in the various makes are that some have movable valves with stationary seats, while others have stationary valves with movable seats, and some have rubber diaphragms while others have metal ones. A common type of regulator is shown in cross section in figure 35. Some type of safety release mechanism, such as a breakable disk or ball relief valve, is provided for the working pressure chamber of every regulator. If the regulator valve fails to close completely, a high pressure will be generated. This condition is sometimes known as "creep." Cylinder pressure gages are provided with safety devices to relieve the pressure if the bourdon tube in the gage breaks. Working pressure gages are usually provided with vent holes for the same purpose.
FIGURE 35.—. Single stage regulator.
c. Pressure reduction operation. —The cylinder pressure is reduced to working pressure as follows : When the pressure-adjusting screw (figure 35) is turned to the left (counterclockwise) until fully released, the high pressure valve is held closed by the small valve spring. When the
cylinder valve is opened, gas from the cylinder enters the regulator through the inlet connection and passes through the inlet screen to the high pressure chamber where it assists the valve spring in keeping the valve seated. The screen keeps out particles of dirt or other matter that might damage the valve seat. As long as the valve is closed, the gas is confined to the high pressure chamber. The cylinder pressure gage is connected to this chamber through a drilled hole and registers the cylinder pressure. When the pres sure-adjusting screw is turned to the right (clockwise), it compresses the pressure-adjusting spring and forces it against the diaphragm and the valve, which is connected to the diaphragm. When the pressure of the pressure-adjusting spring overcomes the opposing combined pressure of the valve spring and the high pressure gas on the head of the valve, the valve opens. Gas then flows from the high pressure chamber through the opening around the valve stem into the working pressure chamber, thence through the outlet and hose connection to the torch. If the torch valve is open, the gas flow will continue at the pressure indicated on the working pressure gage, which is connected with the working pressure chamber. In creasing the pressure by the pressure-adjusting spring increases the pressure in the working pressure chamber. Thus any working pres sure, within the capacity of the regulator, can be obtained by turning the pressure-adjusting screw until the working pressure gage indicates the pressure wanted. The correct torch valve should always be open when the working pressure is being adjusted.
d. Pressure regulation. —The gas pressure in the working pressure chamber to which the torch valve is connected is regulated as follows : If the torch valve is closed, pressure immediately builds up in the working pressure chamber and presses against the diaphragm. The diaphragm, being flexible, moves in or out with changes in pressure in the working pressure chamber. As the pressure on the diaphragm increases, it compresses the pressure-adjusting spring and closes the valve, shutting off the flow of gas. As soon as the pressure on the diaphragm is reduced slightly by opening the torch valve, the pressure-adjusting spring decompresses and reopens the valve. For the sake of simplicity, only the action of the mechanism in starting and stop ping the flow of gas has been explained. Actually the mechanism functions constantly while the torch valve is open. As gas is drawn from the cylinder the pressure in the cylinder falls. The sensitive diaphragm reacts constantly to the gradual drop in pressure and al lows the pressure-adjusting spring to open the valve farther to compensate for this and maintain the working pressure fairly constant until the cylinder pressure is down to the working pressure.
e. Two-stage regulators. —In more recently developed regulators, the pressure reduction is accomplished in two separate steps. This type of regulator has two independent diaphragm and valve assemblies, as shown in figure 36, which makes operation more efficient. The full cylinder pressure enters the regulator and is reduced to a lower pressure in the first stage, which is automatic and nonadjustable. The second stage is the same as the first stage except that it has a larger diaphragm, lighter springs, and is adjustable by the operator. The second stage functions only within a limited range and insures more constant delivery pressure adjustment, than is possible with single stage regulators.
FIGURE 36.—Cross section of two-stage regulator.
f. Oxygen regulator. —An oxygen regulator is designed so that the regulating mechanism will take care of the full cylinder pressure of about 2,000 pounds per square inch. It is customary to provide a cylinder pressure gage with a capacity of 3,000 pounds per square inch on an oxygen regulator. This gage usually has a second scale that indicates the contents of the cylinder in cubic feet at 70° F. For welding, the regulator is designed to deliver a maximum working pressure of 50 pounds per square inch and usually has a working pressure gage with a capacity of 100 pounds per square inch. For cutting, maximum oxygen pressures may vary from 125 to 200 pounds per square inch, so the working pressure gage usually has a capacity of 400 pounds per square inch.
g. Acetylene regulator. — (1) Acetylene regulators operate the same as oxygen regulators, but since the cylinder pressure is not as high as oxygen cylinder pressure, lighter springs are used. An acetylene regulator has a cylinder pressure gage with a capacity of 350, 400, or 500 pounds per square inch and a working pressure gage with a capacity of from 30 to 50 pounds per square inch. Some acetylene working pressure gages are graduated only to 15 pounds per square inch, because it is unsafe to use acetylene at higher pressures. The same acetylene
regulator is used either for welding or cutting. Unlike oxygen regulators, acetylene regulators do not fit all cylinders. Straight 45° and 90° adapters can be obtained for connecting regulators having cylinder connections of certain types and dimensions to cylinder valves of different types and dimensions.
(2) Note that all regulator gages have capacities greater than the pressures they are expected to handle. This excess capacity is provided as a safety factor to prevent the instruments being strained.
(3) The warning "Use no oil" applies to oxygen regulators as it does to all equipment where oxygen is handled under pressure. Use no oil on acetylene regulators because of their nearness to, and possible confusion with, oxygen regulators.
Welding torches
The oxyacetylene welding torch mixes acetylene with oxygen in definite proportions, burns the mixture at its tip, and directs the flame on the parts to be welded or heated.
a. Construction. —The details of construction vary with different manufacturers, but all welding torches are essentially the same. They are made from brass tubing and brass castings or pressure forgings, fastened together by silver solder and threaded connections. Every welding torch has two needle valves, one for adjusting the acetylene pressure and one for adjusting the oxygen pressure. Welding heads or tips are made from drawn copper. Interchangeable tips or heads are usually provided so one torch can handle a wide range of work, from the lightest to the heaviest.
b. Types. —There are two general types of welding torches—low pressure and medium pressure. Acetylene at a pressure of less than 1 pound per square inch is designated as low pressure; from 1 to 15 pounds per square inch, medium pressure. Low pressure torches employ the injector principle. Torches of this type are designed so the high pressure oxygen jet produces a suction effect which draws the acetylene in. Some medium pressure torches are designed to operate with equal pressures of oxygen and acetylene and are called equal pressure or balanced pressure torches.
(1) Low pressure. —A low pressure welding torch is shown in figure 37. Oxygen enters through the oxygen hose connections at the end of the torch and passes through the needle valve and through the tube and passage to the injector jet, which. is in the detachable head of the torch. Acetylene enters the torch at the acetylene hose connection and passes through the needle valve and the tube and passages around the oxygen jet. It is drawn into the injector jet by the suction of the jet and mixes with the oxygen in the expansion chamber. The mixture then passes through the head to the tip where it is burned.
FIGURE 37.— Low pressure welding torch.
(2) Medium, pressure. —A medium pressure welding torch is shown in figure 38. The oxygen and acetylene enter and pass through this torch in about the same way as they do in the low pressure torch. The principal difference is that a mixing chamber is provided in stead of an injector. Here the acetylene, flowing longitudinally, meets the cross current of oxygen flowing in radially through the holes in the sides. (In other models the oxygen flows longitudinally and the acetylene radially.) The cross currents form a whirlpool, thoroughly mixing the two gases as they enter the welding head. The mixture then passes to the tip where it is burned.
c. Interchangeable heads and tips.—One of the valuable features of the modern welding torch is the system of interchangeable heads and tips which allows one torch to be used for various jobs. Tables provided by the manufacturers give the sizes of tips to use for different kinds and thicknesses of metal. A welding torch with five standard interchangeable welding heads is shown in figure 39. These heads are available with detachable tips as shown in figure 40, or with an integral stem. A detachable tip is preferable when it receives rough handling.
FIGURE 39. —Welding torch with interchangeable heads.
FIGURE 40. —Detachable welding tip.
d. Welding accessories. —Welding accessories, such as hose and fit tings, welding rod, flux, goggles, gloves, wrenches, friction lighters, trucks, and tables, should be of good quality and made especially for the purpose. Makeshifts are dangerous. A welding table (fig. 41) while not essential is very convenient.
Setting up equipment
a. Procedure. —So far the functions of individual items of equipment required for oxyacetylene welding have been discussed. The next requirement is to learn how to assemble them properly and safely into a unit ready for operation. This may be done with the usual equipment in 10 steps as follows :
