during the oxy fuel welding process what may be manipulated
The oxidising flame is obtained by increasing just the oxygen flow rate while the carburising flame is achieved by increasing acetylene flow in relation to oxygen flow. Before attempting to do gas welding, learn how to use the equipment and how to regulate the fuel gas and oxygen entering the mixing chamber of the welding torch. Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the U.S.) and oxy-fuel cutting are processes that use fuel gases and oxygen to weld and cut metals, respectively. Gas welding is a simple process, easy to learn and operate, and even a low-skilled operator can do gas welding. Gas welding is not popular for commercial use or thick plate welding since welding quality is inferior compared to other types of welding like arc welding. The goggles and/or face shield protect the eyes from sparks and flying hot metal particles. It is critical that operators using the oxy-acetylene welding or cutting process wear proper gloves and use approved safety goggles or face shield. These gases are used to shield the arc from impurities like air, dust, and other gases; keep welds clean on the underside of the seam opposite the arc (or purging), and to heat metal. Different parts of the gas welding equipment are: Oxygen cylinder (green color) – This cylinder contains the oxygen stored under pressure which is required for combustion. The weld pool area is protected from the atmosphere by the outer zone of the flame. The regulator is connected to the gas torch through a good-quality pressure hose. It can even be employed to cut scaled or rusty plates. Other gases important in welding—nitrogen, carbon dioxide and argon—are also made using this process. The melting point of the metal oxide is less than the melting point of the metal being cut (50% less). oldest welding processes, though in recent years, it has become less popular in industrial applications. Moreover, the welder has a clear view of the weldpool and can work in complete freedom of movement. Oil and grease may ignite spontaneously, when in contact with oxygen. Lower temperatures can be achieved by using … This cylinder has a regulator with two pressure gauges. There is no need for filler material or pressure to create the weld. This temperature provides enough heat to melt most metal. The different techniques of oxy-acetylene gas welding are forward gas welding, backward gas welding, and vertical gas welding. However, other gases such as propane, hydrogen and coal gas can be used for joining lower melting point non-ferrous metals, and for brazing and silver soldering. Preheat flames are used to raise the surface or edge of the steel to approximately 1800°F (bright red color). Flame temperatures can reach 3,200 degrees Celsius. The hose connecting the oxygen cylinder and the welding torch is green, and that connecting the acetylene cylinder and the welding torch is red. There are two pressure gauges on each cylinder. The initial cost of the gas welding equipment is affordable. Gas welding finds its application in many industries, and many of the general applications are listed below. Subscribe to our newsletter to receive the latest news and events from TWI: Oxyacetylene welding, commonly referred to as gas welding, is a process which relies on combustion of oxygen and acetylene. The gas cylinders should be stored with their protective caps on when not in use. Unlike other welding methods, gas welding does not need electricity. The choice of the fuel gas depends on the project type and work. The neutral flame has oxygen and acetylene in equal proportions, and this is usually used for welding. The blowpipe is therefore designed to accommodate different sizes of 'swan neck copper nozzle which allows the correct intensity of flame to be used. The acetylene and oxygen mixture exit from the nozzle to ignite (the welder uses a lighter). You should complete the welding by slowly retracting the flame from the weld joint, allowing it sufficient time to harden without oxidation. Oxygen can also be made by electrolysis of water, but for industrial quantities this is not cost-effective due to the expense of the electricity needed. Backward gas welding (also called rightward gas welding) – This is similar to forward welding, and the only difference is you will start doing the welding from your left and move towards the right. Oxy-fuel combustion is the process of burning a fuel using pure oxygen, or a mixture of oxygen and fuel gas, instead of air. Despite many advanced welding processes available today, oxy-acetylene gas welding is popular even today for welding thin steel sheets (up to 5 mm thickness), for preheating a part, for hot bending, for doing brazing/soldering, and for doing various repair jobs. Oxy-Fuel Gas Welding I. Competencies Given a functional oxy-fuel gas unit, instruction and demonstration of use, each student will be able to: A. Using fuel gas and oxygen, the torch heats the metal pieces to the point that they become molten and join together upon cooling. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Welding is generally carried out using the neutral flame setting which has equal quantities of oxygen and acetylene. Gas welding equipment is very compact and has high portability, the whole equipment fits on a trolley, and you can easily take it to the location required. As the steel is oxidized and blown away to form a cavity, the preheat and oxygen … A standard oxyacetylene torch can be used for oxy-propane; however, it is not recommended. A good gas welder modifies the welding speed to maintain a uniform weld bead size for the complete length of the weld. When it comes to welding thin gauge sheets like car body parts, gas welding is more suitable than other welding methods. Sewalem Gezie. The action of the oxyacetylene flame on the surface of the material to be welded can be adjusted to produce a soft, harsh or violent reaction by varying the gas flows. Three distinct flame settings are used, neutral, oxidising and carburising. OXY-ACETYLENE WELDING It is the common method of gas welding. The heliarc (GTAW) was discovered in November of 1942, and by 1946, together with wire-feed (GMAW), helped pioneer the application of new exotic, materials vital to supersonic flight. Insider’s Guide to Gas Metal Arc Welding (GMAW/MIG), Intermediate Bearing Alignment Checks Using the Blue Contact Method, Top 15 Largest Container Shipping Companies in the World, Insider’s Guide to Gas Tungsten Arc Welding (GTAW / TIG), Insider’s Guide to Shielded Metal Arc Welding (SMAW/MMA), Image Quality Indicators (IQIs) or Penetrameters of Radiography Testing. A neutral flame is chemically neutral. One pressure gauge indicates the pressure of the gas inside the cylinder, and the other pressure gauge indicates the pressure of the gas in the hose. Oxygen-acetylene gas welding was first developed and used in 1903 by the French Engineers Edmond Fouche and Charles Picard. Oxygen-acetylene gas welding was first developed and used in 1903 by the French Engineers Edmond Fouche and Charles Picard. However, oxy-propane cuts faster than oxyacetylene, and cut edges are much cleaner. The oxygen cylinder is made of thick gauge steel to withstand the pressure. The flame trap prevents flames generated by a 'flashback' from reaching the cylinders; principal causes of flashbacks are the failure to purge the hoses and overheating of the blowpipe nozzle. Hydrogen is preferred for underwater welding or cutting. There will be a set of nozzles that can be fitted on the gas welding torch for different applications. Neutral flame – Gas welders use the neutral flame as the starting point. Also known as oxy-fuel welding, oxy-acetylene welding is a process that relies on the combustion of oxygen and a fuel gas, typically acetylene. Where the interpretation of technical drawings is required unit MEM09002 Interpret technical drawing should also be selected. The complete set of equipment is arranged on a trolley for ease of movement and portability. Hoses connecting the gas welding torch with the gas cylinders – The hoses are of good quality and can withstand high pressure. Other Welding Fuels The most common fuel gas used is acetylene. The cylinder has a regulator with two pressure gauges. However, this gas cutting process cannot be used for nonferrous metals and stainless steel. The gas pressures in gas welding are set as per the recommendation of the gas torch manufacturer. And this welding process is still very popular today, mainly because it does not require much equipment, and does not require power. However, the fume levels are minimal and the temperatures produced are much lower than during arc welding. Due to the popularity of acetylene, people often use the phrase ‘oxy-acetylene welding’ or ‘oxy-acetylene cutting’ instead of gas welding or gas cutting. Gas welding is more suitable for the repair of grey cast iron defects when compared to arc welding. The Little Story of the Underwater Cutting. You can see the repair of automobile body parts, exhaust pipe repair done in your local town garage using gas welding. These techniques are very highly skilled and are less frequently used than the conventional leftward technique. Among these four welding techniques, oxyacetylene welding is the most prominent technique adopted for the purpose of welding … In addition, CO 2 concentrations are very high during oxy-fuel combustion. Specially designed safety devices such as flame traps are fitted between the hoses and the cylinder regulators. The color of the LPG/acetylene cylinder and the hose is red, and that of the oxygen cylinder and hose is green. However, it is still widely used for a variety of applications. Oxyacetylene welding, commonly referred to as gas welding, is a process which relies on combustion of oxygen and acetylene. The regulator is connected to the gas torch through a good-quality pressure hose. The gas welding process emits radiation, and hence wearing welding goggles is a must. Definitions given in the Standards include: BS499: Part 1 1991 Glossary for welding, brazing, and thermal cutting. WELCOME YOU FOR THE TOPIC ON: by: C B Singh SCIENCE & TECHNOLOGY OF WELDING ... * Friction/Inertia welding * Ultrasonic welding * Cold welding * Thermit welding * Pressure gas welding * Oxy-Fuel gas welding * Electric Arc welding * Plasma Arc welding * Electron Beam welding * Laser Beam welding * Electro Slag / Gas welding 5. B. However, for nearly half a century prior and half a century since, the common oxy-fuel torch has been a significant mainstay in the aluminum joining process. The gas cylinders are connected to the welding torch through good-quality gas hoses. Each gas is contained in its own cylinder and combined through the use of separate hoses leading from regulators attached to the top of the cylinders. The acetylene and the oxygen cylinders should be appropriately positioned on the trolley, and they should not topple. Practice fire prevention techniques whenever oxy-fuel operations are in progress. Each fuel gas has its characteristics; some fuel gas may burn to reach high temperatures while others may not. A lever controls the additional flow of oxygen through the hole in the center. Similarly, the color of the oxygen cylinder and the hose connecting the oxygen cylinder and the welding torch are green. Copyright © 2021 TWI Ltd. All rights reserved. 33 001 gas welding: Carburizing flame – An excess acetylene added to the neutral flame creates the carburizing flame. Control valves – Both the oxygen and the fuel gas cylinders have their own control valves. The welding torch can also be used for soldering and brazing by changing the nozzles. Identify the major parts of the oxy-fuel gas unit. Gas welding is used in the automotive industry for the welding of the vehicle body, chassis parts, etc. All carbon-containing steels can be oxidized and hence can be cut using a gas cutting torch. This makes it flexible, and you can use it even in remote areas where there is no grid power. The construction of the gas welding torch has two needle valves enabling the operator to fine-tune (adjust) the flow of acetylene and oxygen into the mixing chamber (for delivery of acetylene and oxygen in an equal ratio). Oxy … Care must be taken during all welding processes … Gas welding is suitable and economical for the welding of pipes used for different applications. Gas welding utilizes the heat produced by a gas flame to melt the filler metal, if used, and the base metal, thereby creating a weld. If fuel gas were to leak from the unit, smoking could provide ignition and cause a fire or an explosion. Other fuel gases used are natural gas, butane, and propylene. The cylinders and hoses should have distinct colors to differentiate them. Welding and Cutting Steel Oxy-Acetylene and other methods (3 publications) By John C Bullas. Because steel melts at a temperature above 1,500 deg.C, the mixture of oxygen and acetylene is used as it is the only gas combination with enough heat to weld steel. Control valves control the amount of gas going out of the cylinder, and using the control valves; you can control the ratio of the fuel gas and oxygen mixture. This process is called the fractional distillation of liquid air. The hoses from the fuel and oxygen cylinders connect to the mixer chamber. Oxidizing flame – An excess oxygen added to the neutral flame creates an oxidizing type of flame. Pass a written test on safety and operation procedures on the oxy-acetylene unit with a minimum of 100 accuracy. In this process, a flame is applied to heat the steel to a higher temperature and at the time pure oxygen is applied in a continuous stream and it will create the needed weld. Due to hydrogen embrittlement, hydrogen is not used for welding steel and ferrous metals. An oxyacetylene gas cutting torch is similar to the gas welding torch, has all its features, except that the nozzle used is a special cutting nozzle. The oxidizing flame is hotter than the other two flames. The temperature produced in gas welding is much low compared to other types of welding like arc welding. Forward gas welding (also called leftward gas welding) – You, as a gas welder, holds the welding torch in your right hand, filler rod in your left hand, and do the welding starting from the right and moving towards the left. In this article, we will be discussing the following topics: what is gas welding and how it is done, gas welding machine and its parts, fuel gasses used in gas welding, the difference between the gas welding torch and the gas cutting torch, advantages and limitations of gas welding, application, and safety considerations. Oxy-fuel cutting is a chemical reaction between pure oxygen and steel to form iron oxide. Where arc welding utilizes electricity to create a super-heated arc, torch welding (also known as gas welding and oxy-fuel welding) uses a gas mixture ignited through a torch to melt metal pieces. Do not undertake gas welding or gas cutting in any area where flammable items or goods are stored, specifically highly inflammable substances like oil, gas, gasoline, and other flammable items like wood, paper, etc. Comparing Air-Fuel to Oxy-Fuel Some websites and HVAC/R training manuals recommend the oxy-fuel process over the air-fuel process simply because oxy-fuel burns hotter. The two hoses connect the two cylinders to the welding torch. Before the advent of arc welding with flux coated rods, gas welding was the only process available for good quality welding. You can hold the welding torch and the filler rod at suitable and convenient angles. The cylinders are fitted with regulators and flexible hoses which lead to the blowpipe. As the metal turns hot, it is converted to molten metal oxide and flows away from the cutting zone. Before the advent of arc welding with flux coated rods, gas welding … Oxy-fuel welding is a process that makes use of oxygen and fuel gases to weld metals. Hydrogen – Oxy-hydrogen flame is suitable for welding and cutting aluminum. Founded on the core mission of connecting mechanical engineers globally to share knowledge and experience. You can use gas welding equipment, for gas cutting, simply by using a different torch. The relationship between material thickness, blowpipe nozzle size and welding speed, is shown in the chart. When welding, the operator must wear protective clothing and tinted coloured goggles. Hydrogen can be used for underwater welding and cutting. This cutting nozzle has an outer ring of holes through which the oxyacetylene gas flows and a hole at the center through which additional oxygen flows. Propane is cheaper than acetylene and is easily available; hence, oxy-propane is used for cutting scrap. You can get a temperature of 2000ºC for hydrogen mixed with air at atmospheric pressure and 2800ºC when hydrogen is mixed with pure oxygen in the ratio of 2:1. It produces a flame of temperature 3200ºC (approximately), and this temperature is sufficient to melt the steel workpieces and fuse them together into a strong joint. AN INTRODUCTION TO OXY/ACETYLENE WELDING AND CUTTNG. Gas welding torch – A gas welding torch is where the fuel gas and oxygen are mixed before combustion. Inspect oxy-fuel apparatus for oil, grease, or damaged parts. Gas welding is cost-effective for repair and construction work. The most commonly used fuel gas is acetylene, and many people use the phrase oxy-acetylene welding in place of gas welding. In the neutral flame, the acetylene gas is completely burned in the oxygen and the surrounding air. Gas welding is not suitable for welding thick sections due to the limitation of maximum temperature. As the flame is less intense than an arc and very little UV is emitted, general-purpose tinted goggles provide sufficient protection. Miniature gas torch and small gas bottles find their application in the manufacture of jewelry. Vertical welding – In this type of welding, you will hold the welding torch in your right hand, filler rod in your left hand, and the welding progresses from the bottom towards the top. By Jay Sunga. The oxygen and the acetylene enter the mixing chamber through the hoses, and there is one needle valve each for the entry of oxygen and acetylene into the mixing chamber. Oxygen need not be completely mixed with fuel gas before they leave the tip and create the flame. The three welding processes that falls under oxy-fuel welding are Oxyacetylene welding, Oxyhydrogen welding, Pressure gas welding and air acetylene welding. Never use oil on welding equipment. A harsh forceful flame will cause the molten weld pool to be blown away, while too soft a flame will not be stable near the point of application. Oxy-Acetylene, commonly known as Oxy-fuel, is one of the. It can be described as rapid, controlled rusting. Welding gases are gases produced or used during welding and cutting processes. [8] This process is also great for these applications [9]: Manual rough severing; Automated precision contour cutting; Scrap cutting; Once a welder has the equipment for oxy-fuel cutting, he or she can use it for other processes … Oxy-fuel torches, the materials, construction, safety, performance, test procedures, and marking of which are addressed in CGA E-5-2017 – Oxy-Fuel Torch Standard – Sixth Edition, function to convey and control fuel and oxygen in a safe manner. The gas flame and molten metal emit radiation, and eye protection is very important. This is the best example of how two elements … The complete set of gas welding equipment consists of oxygen and fuel gas stored in individual cylinders, two pressure regulators and two pressure hoses (one for each cylinder), and a welding torch. If you are gas welding zinc-coated sheets, the fumes can be very harmful. Treat the flame with respect. Gas welding can be used for ferrous and nonferrous metal welding. Three are three different types of flames such as neutral/natural, oxidizing, and carburizing. Welding process 1. National Structural Integrity Research Centre, Granta Park, Great Abington, Cambridge, CB21 6AL, UK. Since the nitrogen component of air is not heated, fuel consumption is reduced, and higher flame temperatures are possible. Other fuel gases like propane, hydrogen, and natural gas can be used for welding lower melting point metals like nonferrous metals, brazing, and silver soldering. What Is Oxy-Fuel Cutting Used For? A container ship is a cargo. However, acetylene is not stable for underwater welding or cutting. We'll begin with a brief history of related welding processes, in order to present Oxy-fuel welding in context. Our Authors are qualified Mechanical Engineers, Marine Engineers, Welding Engineers "CSWIP Certified", Coating Inspectors "NACE CIP LII" & NDT Experts "ASNT NDT LIII Certified". The goggles or face shield use special lenses to protect the eyes form light damage. The gas welding torch is designed to accommodate different sizes of copper nozzles (swan neck type) that allow the proper intensity of the flame to be used. Propane or LPG (Liquefied Petroleum Gas) – Oxy-propane is generally used for metal cutting. The oxidizing flame usually is not preferred since it creates unwanted oxides on the metals. Oxy-fuel welding includes those welding operations which use the combustion of a fuel gas and oxygen to provide sufficient heat for fusion welding. A variety of lenses are used depending on the type of welding or cutting that needs to be … When mixed together in correct proportions within a hand-held torch or blowpipe, a relatively hot flame is produced with a temperature of about 3,200 deg.C. The inner cone of the oxidizing flame gets a purple tinge, and the flame sound becomes harsh. Oxy-fuel welding process is a welding techniques utilizing a compressed mixture of high energy density fuel and oxygen to generate a flame capable of elevating the temperature of the material to be welded. Color code – The hoses and gas cylinders used in gas welding are color-coded for easy identification. It comprises oxygen and acetylene gases stored under pressure in steel cylinders. Welding in the overhead and vertical locations usually are slow compared to horizontal locations. OxyFuel Welding Steel The term “steel” may be applied to many ferrous metals which differ greatly in both chemical and physical properties. The defect area can be ground off with a handheld rough grinder, preheated to about 600ºC using gas welding, and then gas welded using a cast iron rod to build up the area. Different fuel gases such as acetylene, hydrogen, gasoline, propylene, and others are used in combination with oxygen for welding or brazing. Gas welding is usually used for thin sheets welding, like automobile bodies, and the initial cost of the equipment is low and affordable. Related Papers. It is useful specifically at places where bottled fuel gas is not available. The increased oxygen reacts with the hot metal, makes the metal get oxidized, and produces more heat to help the cutting process. Oxy-Acetylene welding 101 is part one of Ron Covell's four part welding series, which will give an overview of the most popular cutting and welding processes The flame trap is a safety device and prevents a flame generated by a ‘flashback’ from reaching the gas cylinder. False Chrome plating causes spatter to stick to the tip, prolonging clean-up. These gases do not provide sufficient heat required for welding; however, they can be used for soldering and brazing. Acetylene is the popular fuel gas used in gas welding due to its favorable flame characteristics and high temperature. The welding torch has the mixer chamber at one end and a nozzle at the other end. Filler metal is added wherever required. The welder can adjust the action of the gas flame on the surface of the weld metal by producing a soft, harsh, or violent reaction (by varying the flow of acetylene and oxygen). Before you remove the regulator from the cylinder valve, close the cylinder valve and release the gas left out in the regulator. Gas welding is one of the oldest and most versatile welding processes, but in recent years it has become less popular in industrial applications. This lever (for oxygen) does not exist on the gas welding torch. You might hear this type of welding referred to as “gas welding.” Gas welding is used almost exclusively for welding thin metal sections. Pure oxygen was used instead of ordinary air to increase the flame temperature. The gas welding fumes generated during the welding can be from the work material, filler material, and fluxes. Oxy-acetylene is the typical combination used in gas welding and is generally chosen for general cutting and welding work including work to repair rips and tears in metal. The valves are used for fine-tuning the ratio of fuel gas and oxygen. However, a part of the metal oxide clings to the cut surface as slag, and this can be removed with a chipping hammer or grinding. Acetylene is the commonly used fuel gas, and when correct proportions of oxygen and acetylene are mixed in a gas welding torch, you will get a hot flame of around 3200º C. You can vary the proportion of acetylene and oxygen to get the desired type of flame. Gas welding is not suitable for welding tough steels. Gas welding can be done with or without using a filler material. You can hold the welding torch and the filler rod at suitable and convenient angles. Open cylinder valves correctly. Flame traps – Typical flame traps are fitted between the hoses and the regulator on the cylinder. The rightward technique finds application on plate thicknesses above 5mm for welding in the flat and horizontal-vertical position. The gas welding torch is used for gas welding and is typically carried out by burning an equal volume of the fuel gas (acetylene) and oxygen. There are of course practical limits as to the type of flame which can be used for welding. The harsh, forceful flame may blow away the molten metal from the weld pool, and a flame that is too soft will not have the stability. When carrying out fusion welding the addition of filler metal in the form of a rod can be made when required. The major causes of flashbacks are overheating of the gas welding torch or failure to purge the hoses. These hoses then lead to the torch where they are attached to create the mixture needed … Pressure gauges – There are two pressure gauges on each cylinder (oxygen and acetylene). The flame reaches a temperature of 3200ºC (approximately) which is sufficient to melt steel and other metals. A mixture of fuel gas (normally acetylene) and oxygen undergoes combustion. The all-positional rightward method is a modification of the rightward technique and is ideally suited for welding steel plate and in particular pipework where positional welding, (vertical and overhead) has to be carried out. Always wear your safety gear such as goggles, shoes, an apron, a safety helmet, and hand gloves.