Chapter 17 Oxyfuel Welding and Cutting Equipment, Setup, and Operation © 2012 Delmar, Cengage Learning Objectives • After completing this chapter, you will be able to: – Identify all of the components and equipment found in a typical oxyfuel welding station – Demonstrate the proper assembly, testing, lighting, adjusting, and disassembling of an oxyfuel system – List the proper safety procedures for setting up and operating an oxyfuel system © 2012 Delmar, Cengage Learning Introduction • Oxyfuel welding (i.e., oxyacetylene or oxyfuel welding) – One of the oldest welding processes • Gases other than acetylene can be used • Acetylene is the most popular – Welding, cutting, brazing, hard surfacing, heating, and other similar processes • Same basic equipment and safety procedures © 2012 Delmar, Cengage Learning Oxyfuel Equipment • Pressure regulators – Reduce high pressure to proper lower working pressure • Keep lower pressure constant over a range of flow rates – Several types • Work the same • Not interchangeable © 2012 Delmar, Cengage Learning Oxyfuel Equipment (cont’d.) • Regulator operation FIGURE 17-1 Force applied to the flexible diaphragm by the adjusting screw through the spring opens the high-pressure valve. © Cengage Learning 2012 © 2012 Delmar, Cengage Learning FIGURE 17-2 When the gas pressure against the flexible diaphragm equals the spring pressure, the high-pressure valve closes. © Cengage Learning 2012 FIGURE 17-3 A drop in the working pressure occurs when the torch valve is opened and gas flows through the regulator at a constant pressure. © Cengage Learning 2012 © 2012 Delmar, Cengage Learning Oxyfuel Equipment (cont’d.) • Pressure gauges – Working pressure gauge shows regulated pressure being controlled for the torch – Cylinder pressure gauge shows remaining cylinder pressure • Regulator safety pressure releases – Prevent excessively high pressures from damaging the regulator © 2012 Delmar, Cengage Learning FIGURE 17-4 Two-stage oxygen regulator. Thermadyne Industries, Inc. © 2012 Delmar, Cengage Learning FIGURE 17-5 Safety release valve on an oxygen regulator. Thermadyne Industries, Inc. © 2012 Delmar, Cengage Learning FIGURE 17-6 Pressure release valves. © Cengage Learning 2012 © 2012 Delmar, Cengage Learning Oxyfuel Equipment (cont’d.) • Regulator safety practices – Pressure-adjusting screw • Backed off at shut down – High-pressure valve seats that leak • Result in a creep or rising pressure on the working side of regulator • Leak detection – Leak-detecting solution • Must be free flowing © 2012 Delmar, Cengage Learning Oxyfuel Equipment (cont’d.) • Regulator fittings – Variety of designs • Regulator use and servicing – No moving parts require oiling – Adjusting screw can be removed and cleaned with a dry, oil-free rag – Gas pressure must be released and adjusting screw backed out when cylinders are turned off © 2012 Delmar, Cengage Learning FIGURE 17-7 (A) Acetylene cylinder valve (left-hand thread). (B) Oxygen cylinder valve. (C) Argon cylinder valve. (D) Carbon dioxide (CO2) cylinder valve. Larry Jeffus © 2012 Delmar, Cengage Learning Design and Service of Welding And Cutting Torches • Oxyacetylene hand torch – Most common type of oxyfuel gas torch used for welding and cutting • Purchased as a combination welding and cutting torch or a cutting torch FIGURE 17-13 A combination welding and cutting torch kit. Thermadyne Industries, Inc. © 2012 Delmar, Cengage Learning Torch Care and Use • Threaded connections – Must be protected • Hose connections – Should not leak • Valve stem packing – No gas should leak past – Easily repaired © 2012 Delmar, Cengage Learning FIGURE 17-14 One hose fitting will protect the threads when the other nut is loosened or tightened. Larry Jeffus © 2012 Delmar, Cengage Learning Welding and Heating Tips • Considerations – Become familiar with hole size in the tip • Larger diameters: higher heating capacity • Heating capacity: determines thickness range • Tip sizes: can be compared to the numbered drill size used to make the hole FIGURE 17-16 A variety of tip styles and sizes for one torch body. Larry Jeffus © 2012 Delmar, Cengage Learning Tip Care and Use • Metal-to-metal seal tips – Must be tightened with a wrench • Tips with an O ring or a gasket – Tightened by hand • Dirty welding and cutting tips – Cleaned using a set of tip cleaners or tip drills © 2012 Delmar, Cengage Learning FIGURE 17-19 Cleaning a tip with a standard tip cleaner. © Cengage Learning 2012 © 2012 Delmar, Cengage Learning Backfires • Flame goes out with a loud snap or pop – Problem must be corrected before relighting • Causes – Touching the tip against workpiece – Overheating the tip – Operating when flame settings are too low – Loose tip or dirt in the tip – Damaged seats © 2012 Delmar, Cengage Learning Flashbacks • Flame burns back inside the tip, torch, hose, or regulator – Produces a high-pitched whistle – May cause a fire or an explosion if it reaches the cylinder • Close torch oxygen valve • Close fuel-gas valve • Allow torch to cool off © 2012 Delmar, Cengage Learning Reverse Flow Valves FIGURE 17-21 Gas may flow back up the hose if both valves are opened at the same time when the system is being bled down after use. Installing reverse flow valves on the torch can prevent this from occurring. ESAB Welding & Cutting Products © 2012 Delmar, Cengage Learning Flashback Arrestors • Stops reverse gas flow and flashback flame – Sensitive to backpressure • Servicing reverse flow valve and flashback arrestor – Both must be checked on a regular basis © 2012 Delmar, Cengage Learning FIGURE 17-22 (A) Acetylene. ESAB Welding & Cutting Products (B) Oxygen combination flashback arrestors and check valves. ESAB Welding & Cutting Products (C) Replacement cartridge for flashback arrestor. ESAB Welding & Cutting Products (D) Torch designed with flashback arrestors and check valves built into the torch body. Thermadyne Industries, Inc. © 2012 Delmar, Cengage Learning Hoses and Fittings • Welding hoses – Molded together • Fuel gas: red with left-hand threaded fittings • Oxygen: green with right-hand threaded fittings • Hose use and servicing – Gas must be turned off when not in use – Keep out of direct flame, sparks, etc. – Hose fittings can be replaced © 2012 Delmar, Cengage Learning Oxyfuel Equipment Setup and Operation • Before using oxyfuel equipment for the first time – Read and follow manufacturer’s safety and operation manual • Setting up an oxyfuel torch set – Refer to Pages 400-402 of text • Turning on and testing oxyfuel welding equipment – Refer to Pages 402-404 of text © 2012 Delmar, Cengage Learning Types of Flames • Oxyacetylene flame settings – Carburizing, neutral, and oxidizing • Lighting and adjusting oxyacetylene flame – Turn regulator adjusting screws until working pressure gauges read 5 psig – Turn on the torch fuel-gas valve – Light torch and increase flow of acetylene – Adjust torch © 2012 Delmar, Cengage Learning FIGURE 17-41 Correct position to hold a spark lighter. Larry Jeffus © 2012 Delmar, Cengage Learning Shutting Off and Disassembling Oxyfuel Welding Equipment • Steps – Quickly turn off torch fuel-gas valve – Turn off oxygen valve and cylinder valve – Open one torch valve at a time to bleed off pressure – Close both torch valves and back both regulator adjusting screws out – Loosen hoses and regulators and unscrew – Replace valve protection caps © 2012 Delmar, Cengage Learning Summary • Oxygen and acetylene welding equipment and process – Around for hundreds of years – Brink of extinction for commercial applications – Still flourishes in small shops, art studios, automotive repair services, etc. – Great basis for learning other welding processes © 2012 Delmar, Cengage Learning
