Chapter 14 Oxyfuel Gas Cutting 411 connected to oxygen and fuel gas cylinders. Review Chapter 13 for a more complete description of the oxyfuel gas cutting torch and cutting torch attach- ment shown in Figure 14-3. This chapter deals only with the procedure for oxyfuel gas cutting. See Chapter 23 for other methods of cutting. In an oxyfuel gas cutting torch, the preheating fl ame(s) comes from one or more of the torch tip’s orifi ces arranged around a central oxygen orifi ce. Figures 14-2 and 14-3 show two different designs of cutting torches. The welder controls the cutting oper- ation using the cutting oxygen lever. In operation, a preheating fl ame is maintained at the tip through small orifi ces arranged around the cutting oxygen orifi ce. Cuts are made by depressing the cutting oxygen lever on the torch, which controls the fl ow of oxygen from the center orifi ce, as shown in Figures 14-4 and 14-5. Before the cutting torch is turned on, the desired cutting tip must be inserted into the torch and aligned. Most cutting tips have an even number (2, 4, 6, 8) of preheating orifi ces. For the best cutting quality, two of the preheating orifi ces are aligned with the cutting line and the others are set on each side of the cutting line. See Figure 14-6. There are two different types of oxyfuel gas cutting torches: Positive-pressure torch. Injector-type torch. Procedure for Lighting a Positive- Pressure Oxyacetylene Cutting Torch The following is the proper procedure to follow for purging an oxyacetylene cutting outfi t and lighting a manual positive-pressure cutting torch: 1. Check the condition of all equipment. 2. Inspect the regulators. Turn adjusting screws all the way out (regulator closed). 3. The welder should stand to one side of the gauges. Open the oxygen cylinder valve very slowly until the regulator high-pressure gauge reaches its maximum reading. Then, turn the cylinder valve all the way open to close the double seating (backseating) valve. Figure 14-3. A standard cutting torch attachment that quickly attaches to a torch body. (Uniweld Products, Inc.) Oxygen cutting valve Figure 14-4. A cross-sectional drawing of cutting torch with preheat mixing chamber located in the torch body. (ESAB Welding and Cutting Products) Cutting oxygen Mixing chamber Cutting oxygen lever Cutting oxygen valve
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