Gas Welding

Gas Welding Supplies

Perhaps because of its history going back to the turn of the century, or perhaps due to its appearances in films and other popular imagery, gas welding/cutting has the most "romantic" image of the various systems we'll deal with. When most people conjure up a vision of a welder, it is of a perspiring, leather-clad man wearing dark goggles and wielding a flaming torch with sparks flying everywhere. In truth, this is more likely a picture of someone cutting with a torch, but it points out the ubiquitous nature of the gas equipment in the overall picture.

Although losing some ground to modern electric welders in the most recent decade as the system of choice for the average home/shop user, oxy-acetylene equipment is still unarguably the most versatile setup for home, farm or shop.

Gas Welding and Welding Supplies
Besides its function as a fusion-joiner of metals, gas equipment also of course is extremely valuable as metal cutting equipment, and can also be used for non-fusion metalwork such as brazing, soldering, and the dying art of automotive body lead work. It is also useful equipment in any automotive shop for freeing rusted fasteners, heating machined parts that require a hot shrink-to fit connection (like a gear on a shaft) and heating metal parts prior to bending them. It requires no water or electrical connections, making it one of the most portable of systems, you can load it into a pick-up truck and take it to any remote location. If the gas hoses are long enough, the welder can climb up a pole or down a shaft to perform welding or cutting, a flexibility few other systems can match. The basic gas process When gasses are used in other types, they are usually of the inert kind, like argon, CO2 or helium, which are involved in the process only to keep the molten weld puddle clear of impurities from the air during formation. In oxy-acetylene, however, the 3.1 Versatile gas-welding equipment has been a mainstay of metal fabricating for most of the 20th century, and little has changed with procedures or equipment. The basics, fusing metals at their melting point, are still valid for many uses in farm, industry and home/shop hobby applications.
Oxyturbo 110 Gas Welding Kit Oxyturbo 200 Gas Welding Kit

OxyTurbo 110

OxyTurbo 200

You'll find helpful people at your local welding supply shop that can set you up with torch equipment, oxygen and acetylene bottles, and other supplies you'll need. Oxygen, while not exactly flammable by itself, is the gas necessary both for us to breathe and for any type of combustion to take place. Combustion is really nothing more than very rapid oxidation, and if pure oxygen is directed at some thing flammable, a fire can start very easily. Some inexperienced welders have been know to dust off their work clothes with their unlit torch, but the extra oxygen that gets into their clothes can make it so flammable that any tiny spark could start the clothes on fire. Likewise, oxygen must be kept away from things like oily rags or any petroleum products. Oxygen as used in welding equipment is generally stored in high-pressure, 1/4-inch-thick-walled steel cylinders 2200 psi. While oxygen may be important for our lungs to work, it can still be dangerous if too much is introduced to the bloodstream. For this reason, oxygen should be kept away from open cuts such as you might have on your hands. Acetylene, on the other hand is flammable to the point of being explosive and is also mildly poisonous, causing nausea and headaches if you breathe much of it. Pressure in the acetylene cylinder is much less than with oxygen, at 250-325 psi, but the construction of the cylinder is different. Acetylene cylinders are shorter and fatter than oxygen bottles, and are constructed in two halves. Because acetylene is unstable at high pressures, the only way to get sufficient quantities into the standard bottle is to dissolve the acetylene in another medium. In welding tanks, the two halves are filled with an asbestos/cement mixture and then welded together. After baking, the material forms a honeycomb inside the tank. Liquid acetone is put into the tank because it will absorb 25 times its own volume in acetylene, thus stabilizing the acetylene. Because of the differences in chemical action and storage of oxygen and acetylene, there must be no mix-ups between the two. For this reason, the tanks are made in different proportions and different colors; the acetylene bottle has only left-hand threads, and the hoses for each bottle are different i.e. red hose for acetylene, blue hose for oxygen. Both bottles have a threaded top for filling and connection of the regulators, and due to their high internal pressure, especially the oxygen cylinder, gas bottles should always be stored securely. If a bottle were to fall from a truck onto concrete, for instance, the regulator could be knocked off, suddenly releasing enough gas to propel the heavy bottle around like a kid's balloon, except with potentially deadly force. In addition, the acetylene bottle should always be stored in an upright position. If stored laying down, some of the liquid acetone inside could be drawn out of the bottle into the welding supply, ruining the weld.
Oxygen Hose Fitted Acetylene Welding Hose 10mm Fitted Propane Hose 10mm
Fitted Oxygen Welding Hose 10mm Fitted Acetylene Welding Hose 10mm Fitted Propane Hose 10mm
The equipment besides the two gas bottles, there are gauges/regulators, hoses and the torch itself. Each tank has it's own set of two gauges mounted on a regulator body designed to reduce the high cylinder pressure down to a useable pressure for the torch. On each tank, there is. The bottles are fitted with valves, to which regulators are attached. This is a cutaway of an oxygen cylinder valve, showing the way the valve seals internally. Oxygen cylinder valves seal best when either closed or fully open. There are two basic types of regulators found on setups, single-stage and two-stage. The former type reduces the cylinder pressure to a working pressure in just one step, say from oxygen's 2200 psi to 3 psi for the torch. In the two-stage regulator, the first stage reduces pressure to about 30 psi; the second stage adjusts pressure from there down. A great portion of the expense in a setup comes from the gauges/regulators, and better ones simply cost more. The simpler-to-manufacture single-stage regulators cost less and are therefore commonly found on the lessexpensive kits for oxy-acetylene welding. They work fine for most purposes, and their only drawback is that the regulation depends heavily on the pressure inside the tank. As the tank pressure goes down as the gas is used up, the regulation changes and must be adjusted again. Also, when doing a job that requires a lot of gas flow, such as large welds or cutting/heating thick plates, the single-stage regulator may not be able to keep up. The more expensive two-stage regulators maintain gas flow to the torch
with less fluctuation, which is important in a professional welding operation but may not be a big factor in home/shop welding if you don't work on heavier materials. Obviously, gas-welding sets with two-stage regulators will cost more initially than the single-stage kits. The hoses for a gas-welding setup are specially-designed to carry the oxygen and acetylene gasses. While they do not handle the very high tank pressures, they are built in three layers to withstand the regulated pressures for many years with proper care and maintenance. As mentioned above, the hose for carrying acetylene is red, while the oxygen hose is green, and the acetylene hose has left-hand threads on its fitting, so there is no chance of mixing them up when making connections (Note: Left-handed fittings generally have a groove cut in around the fitting, to differentiate them from normal, right-hand fittings). Doing so could be disastrous, since any residual flammable gas or other material in a hose connected to pure oxygen could cause the hose to ignite or explode. For this same reason, it is important that no lubricants or chemical compounds of any kind be used on the hoses or fittings. Packages may contain hoses around 10-12 feet long in the economy or light-duty kits, and 20-25 feet long in the heavier, more professional sets. Extension hoses can be added to your starter set if you need to reach areas further from your tanks (see illustration). 3.12 In industrial situations, like this oilfield service truck, gas setups may be equipped with large cylinders and 100 feet of hose, to handle any situation. The torch for oxy-acetylene welding is a precision-made tool, usually constructed with a forged brass body, two knobs controlling the gas flow, and copper tips of varying size. In use, the two gasses flow through valves controlled by the knobs, and mix inside the torch with the combined gasses coming out of the tip in an oxygen-to-acetylene ratio controlled by the weldor. The weldor changes tips, each of which has a carefully sized opening, to suit the flow and flame shape required for a particular job. The makeup of the cutting torch is different from the welding torch and will be discussed later on. Gas sets can be purchased three ways: as a welding-only setup, a cutting-only setup or a combination set with two torches. The type you choose will depend on your needs. If all you need to do is weld up animal corral fencing made from steel pipes, you may use a cutting-only set for cutting pipe to length and shaping the cut ends to fit against the next pipe, and use a generator-driven arc welder on your truck for joining the pipes. However, if you are doing automotive sheet metal work or metal sculptures with relatively-thin materials, you will probably do most of your cutting with an electric shear, hand tin snips, hacksaw, etc., and only require a torch for welding, brazing and occasional heating. A combination set is of course the most versatile. Most sets that you buy can be fitted with a different torch at any time, so if you decide to buy a welding-only setup, you can purchase a cutting torch later on if your need to. After you purchase your welding package, you will have to buy or rent tanks.The standard-size oxygen and acetylene tanks will hold enough gas to last the home/shop user for a long, long time. The tanks must be hydrostatically-tested periodically, which involves filling them with water to a certain pressure to test for safety. When the test is due, your local supply cannot refill your tank until it is tested. When you buy new tanks outright, you then become responsible for the testing costs and any cylinder-valve repairs, while if you lease the cylinders, the company takes care of that as part of the lease agreement. Leasing the cylinders allows you to get started welding with the minimum investment, because outright purchase may be expensive. However, if you add up the monthly rent There are usually three sizes of tanks, small (80 cu. ft.), medium (150 cu. ft.) and large (275 cu. ft.). The small tanks are the easiest to store and maneuver around the shop and are fine for most occasional users. The medium tanks will be more than enough for most any home/shop use, lasting more than a year under normal use. The largest tanks are heavy, and more difficult to move around the shop. Getting started with oxy-acetylene Thoroughly read all the directions that come with your setup before you do anything. If you have purchased a used welding set from someone, make sure the instructions are included, or have an experienced person help you get set up. Compressed gasses are dangerous; so is the welding process, and there are many more safety considerations to understand than we can cover here in this book. Obviously, since we are dealing here with a very hot flame and the promise of flying sparks, you should have a clean work area away from any flammable materials and a good fire extinguisher should be handy, as well as a source of water. If a spark gets onto your shoe, don't waste your extinguisher on that. Use a water spray bottle, which is also handy at times for cooling off a piece of metal. Follow your set's directions for attaching the gauge/regulator sets to your filled bottles of oxygen and acetylene. The bottles should be secured with a sturdy chain to either your bench or a welding cart that has provisions to keep it from tipping over easily. Before the regulators are attached, blow any dust out of the cylinder valves by cracking them. You should stand to the side of the cylinder when doing this, with the outlet pointed away, and very quickly open the valve slightly and close it again. Just a little blast of gas will ensure that the connection is free of dust. Use a proper-fitting wrench (not an adjustable) on all your regulator and hose connections, which are usually brass fittings, and remember that the acetylene connections are left-hand threaded. Blow out the regulator by slowly opening the cylinder valve when the pressure-adjusting screw (usually T-shaped) is turned out all the way. One gauge will show you the cylinder pressure, and the other the hose/torch pressure.
Argon Gas Regulator - 2 Gauge Oxygen Gas Regulator - 2 Gauge Acetylene Gas Regulator - 2 Gauge
Argon Gas Regulator - 2 Gauge Oxygen Gas Regulator - 2 Gauge Acetylene Gas Regulator - 2 Gauge

Attach the hoses and blow them out with a blast of gas. Adjust the regulators to provide 2-3 psi working pressure from each bottle. The cylinder valves should always be opened slowly, with your body away from the ends, and the oxygen valve should always be opened all the way. It is of a type that seals best either fully closed or fully open. The acetylene valve should be opened only about 1-1/2 turns. Connect the hoses to your torch with the cylinder valves closed. In most cases this involves wrenches, but there are some professional sets that have snap-on connections (like air line hoses) to make quick, wrenchless work of changing torches. Select a medium tip from your set (your set's instructions will recommend what gas pressure works with which tip and what thickness of metal they are suited for) and attach to the torch. After everything is assembled, you can test the connections with soapy water for leaks. You will need something to light the torch flame, and a wire-framed metal striker should have been included with your set. Never use open flames such as a cigarette, cigarette lighter or match to start your torch! Your fingers need to be well out of the way. You should be wearing leather gloves and heavy clothing with leather shoes or boots. Do not tuck your pants into your boots, or you could create a pocket there that could collect sparks. Likewise, do not wear pants with cuffs, for the same reason. Have your colored welding goggles on your head, but not yet over your eyes. This is a very important step in gas welding, and one you will be making every time you pick-up the torch to weld, braze, cut or solder, so you'll have to practice this to the point where it becomes second nature. Open the cylinder valves slowly as described before, and make sure the regulated pressure is set correctly. Hold the torch in your operating hand (right, if you are righthanded) and the striker in the opposite hand. Both valves on the torch are closed. Open the acetylene valve on the torch about a half-turn and operate the striker near the torch tip. There should be a flame with some sooty flying particles. Quickly add some oxygen and the soot should disappear. Study the illustrations of flame type. What you have right now is a carburizing flame, which is overly-rich in acetylene. As you add more oxygen, the flame characteristics will change. While the rich mix gives you a wide, flared-out yellow flame, adding oxygen will make the flame narrower and brighter. The ideal flame for most is a neutral flame, which is neither carburizing nor oxidizing (too much oxygen). When you have adjusted the torch properly, there will be a large flame graduating from blue at the end away from the tip down to white near the torch and with an inner cone that should be light blue. If you add too much oxygen, the inner cone will be smaller, pale in color, and there may be a hissing sound. You'll need to practice achieving the neutral flame, and when you start welding, you'll see what happens to metals when the flame is incorrect. The proper method of shutting off the torch is equally important. Close the acetylene valve on the torch first, then the oxygen. If you do it the other way around, there could be a small amount of gas left in the tip that could ignite. If you are through welding for some time, it is good safety practice to then close down the gas cylinder valves as well, but if you are going to weld again in a short while, just shut off the torch valves only. You'll need a lot of small pieces of clean scrap metal to practice on, of varying thicknesses. Even if you only intend to do light sheet-metal welding, start by practicing with thicknesses up to 1/4-inch to become familiar with different tip sizes and flame adjustment. The cleaner the scrap pieces, the better your welds will be, and this applies to any type of welding, gas or electric. You should sand or grind the areas to be welded to remove any paint, coatings or rust. You should not use for testing any metals that are galvanized or coated with zinc, or any kind of plating. Not only will welding be dirty and difficult, but the coatings may cause harmful gasses when vaporized in the weld. Start your first exercise with a piece of steel on a level, non-flammable surface, not a wooden bench. The ideal work area would be a steel table (not just a wooden bench with thin sheet metal nailed onto it) with some firebricks on top. The firebricks can be obtained at your welding supply center, and, in addition to being non-flammable, they do not suck the heat out of your sample like a steel table, and there's no chance you're going to weld the sample to the brick. It can be very embarrassing when you practice on a steel table and you have various scraps welded - stuck to your table. With your torch adjusted properly, pull down your goggles and put the torch tip about one inch from the steel and just try to make a long weld puddle of molten metal. The torch should be leaning back at a 45-degree angle, with the flame pointing in the direction the bead is going. When the steel starts melting into a small pool where you started, move the tip along and give it a rhythmic motion of an oval shape as you go, trying to follow a straight line, blending the newly-heated edge of the puddle with the back edge of the puddle. The process will leave a line of rippled ridges. If you are burning holes in the metal, there may be too much oxygen, the torch may be too close to the metal, the tip could be too large or you are possibly advancing the torch too slowly. If you go too fast, have the torch too far away or the tip is too small, your puddle will be very small and it won't penetrate the metal very far. The more the torch is pointed straight down at the metal (no angle) the deeper the penetration will be, and vice-versa. Practice at different angles until you can make a bead, with even ripples and proper penetration. Of course, not all of your welding will be done this way, in fact almost all of your real welding will involve adding filler rod, but for now you need to learn torch control and rhythm. Many of the projects you encounter will involve welding along an irregular line, especially in repair work, where you are welding up a crack. To become more familiar with making a bead along an irregular line (still without filler rod) draw a zigzag or curved line on the steel with soapstone and practice making a good bead. Proper hand control is everything in. Your hand must be comfortable and steady at all times. In welding classes, students are often challenged to write their first name in script with welding bead on a piece of metal, which challenges you in handling changes in bead direction. When you are successful with these experiments laying down a good bead on the metal, you're ready to try joining two pieces using a filler rod. This requires not only good torch control, but control of your other hand as well with the filler rod. Generally, the filler rod should be the same material as the base or parent metal for good fusion welding. If you weld aluminum, the filler rod must be aluminum, and steel rods are used on steel. The steel filler rods are coated with copper to keep them from rusting and to make cleaner welds. As a basic rule, select a filler rod that is the same diameter as the thickness of the metal you are welding. Most light metals are welded with 3/32-inch, 1/16-inch or 1/8- inch rod, and you will probably never gas-weld with anything bigger than 1/4-inch rod. To weld thick materials, several passes are required to make a good fusion, and various forms of electric welding are usually much faster than a torch at making multiple-pass seams. Gas welding/cutting Welding with filler rod Let's say that you need to join two pieces of 1/8-inch-thick metal in a straight bead from right to left. Position the two pieces such that they are butted together where they are to be joined, and that you have something blocking or clamping them in place so they won't move as you weld. Start your weld puddle at the right end of the seam, and as the puddle develops, use your left hand to insert the tip of the filler rod into the center of the hot puddle, then pull it out right away. Set up a rhythm of alternately putting in the rod and taking it out as the bead progresses to the left. When we describe the puddle, the edge of the puddle closest to the direction you are traveling is the front edge, while the part of the puddle you just finished is the rear. If you have ever done any soldering, you may have a bad habit of heating the solder with your torch or soldering iron and letting the molten lead drip onto the joint. This is a bad habit and one you shouldn't bring with you in your welding practice. The molten puddle should melt the filler rod, not the torch. If the rod sticks, then you are not keeping the puddfe molten enough, or you are adding filler rod too fast, either of which will result in a low-quality weld. This skill of making a good bead, with evenly overlapping ovals and good penetration will take considerable practice, but if you learn two-handed gaswelding techniques well, any other welding system you pick up later on will be considerably easier to learn. Most of the welding you will do will be forehand welding, in which you angle the torch so that the flame is aimed somewhat toward the direction of the desired weld bead. This preheats the metal as you go and makes addition of filler rod to the front edge of the puddle easier because it is truly hot. Sometimes it seems like keeping the proper torch distance, moving at the right speed, circling or ovaling the tip and dipping the rod in at the right time is just too much to concentrate on at one time, but you will get the hang of it. This isn't "brain surgery" and millions have learned before you. After a good long practice session, begin to examine things around you that are of welded construction and you'll get an appreciation of the practice it took to lay down those beautiful beads that look like they were done by some machine instead of human hands. Indeed there are some kinds of welding that are done with largely robotic welding machines, but a good weldor can make virtually perfect joints that are stronger than the parent metal. We mentioned before that cleanliness is critical in making good welds. The two edges to be joined need to be sanded or ground clean to bright metal and should fit as closely as possible. Small gaps are inevitable in some kinds of work and can be bridged with filler rod, but gaps should be kept to a minimum. On thicker materials, you will find that it is easier to make a clean weld with good penetration if the edges of the two pieces are beveled before you weld. This can be done with a file or grinder. Thin materials have their own idiosyncrasies, mostly to do with keeping the two edges in alignment. As you progress with your weld bead, more and more heat travels out into the parent metal, so that after welding for some distance, the metal you now encounter is hotter than the metal you started on, so you may have to adjust the torch away slightly to compensate for the puddle forming faster. Another problem with thin materials is that the parent metal tends to distort with the application of heat. Metal expands when heated, and two edges that were parallel when you started welding probably won't stay that way. Usually, the edges pull away and you have a gap to bridge that wasn't there when you started. The solution is to tack-weld at intervals before applying too much heat. A tack-weld is simply a bead only one or two puddles long, done quickly. To join a long seam in sheet metal, tack the ends first, then the middle, and then put tacks every few inches apart, while alternating the ends you tack. When you go along later to do the final, full seam welding, the tack puddles can be melted into the main seam as you go, and the pieces will stay aligned the whole way. This is particularly important when joining long sheet-metal seams like welding a new quarter-panel onto a car. In auto bodywork, you need to keep the warpage to a minimum. In some cases when doing the final seam after tacking sheet metal, you may stop after a few inches are welded and quickly apply a body dolly to the backside of the weld area and hammer on the weld area on top with a body hammer. This "hammer-welding" (alternating welding and hammering) technique straightens the seam and the two panels while they are still hot and pliable, and the resultant seam when done by a good body man requires much less grinding or filling to make it ready for primer and paint. The basic joint we have illustrated is a buff joint, where two pieces of metal are pushed together and welded along the seam where they meet. There are many kinds of joints, and it is helpful to try welding a few other types after you have practiced enough on butt welds on thick and thin materials. Corner welds, where the two edges meet at an angle can be either inside or outside corners. The outside corner weld is the easier to perform because you can see the seam so clearly, and the pieces need not be beveled. Just placing them so that the edges form a groove or V will do it. On inside corner welds, depending on the angle involved, the action is harder to observe, being shrouded somewhat by the pieces. After you have practiced on these more difficult welds, try a lap weld. This is where the two pieces lay over each other (overlapping). You run a bead where the joint is, and depending upon the strength required for the application, you may want to weld the seam on the other side as well. In auto bodywork, sometimes panels have to be overlapped instead of butt-welded, but in such cases the backside seam is seldom welded. When making welds with filler rods, you will run across situations where the rod gets short enough for your left hand to get too close for comfort to the heat of the welding. Before making a bead, practice will have shown you how fast the welding rod gets used up and how long a rod you will need to complete the seam. Start with a rod long enough to do the whole seam. If the seam is longer and will take several rods to complete, you will have to stop welding and get a new filler rod. It will take some time and practice to get the hang of continuing a bead with a new rod where you left off before. The trick is to make the whole bead look like a continuous weld, without little piles of buildup where you stopped and restarted. When a rod gets short, many welders simply tack the short piece onto the end of a new rod and go right on welding. When you get good at it, the bead won't have a chance to cool off too much. In insidecorner welding, you may want to take the welding rod and put a bend into it, such that it puts your hand in a more comfortable position, further away from the heat of the action