Chapter 14 Oxyfuel Gas Cutting 417 The operation of the torch with the cutting attachment is the same as the operation of a regular cutting torch. Figure 14-3 shows a cutting attachment and Figure 14-15 shows a cutting attachment installed on a torch body. There are usually two torch oxygen valves, one torch acetylene valve, and a cutting oxygen lever involved when a cutting attachment is used. The welding torch body has an oxygen valve and a torch acetylene valve. The cutting attachment has a torch oxygen valve and a cutting oxygen lever. To make fl ame adjustments, the torch oxygen valve on the cutting attachment should be opened one or more turns. The torch valves on the torch body are then used to adjust the fl ames. Caution: The torch valves on the welding torch body must be turned off before the cutting attach- ment is disconnected. 14.5.2 Cutting Tips Cutting tips normally have at least two orifi ces. One orifi ce, which is usually in the center of the tip, is for the cutting oxygen. One or more smaller orifi ces are for preheating the metal to be cut. Cutting tips can be made of one-piece or two-piece construction. One-piece tips are used for oxyacetylene cutting only. Two-piece tips are used for all other gas cutting: natural gas, propane, LP gas mixes, etc. For satisfactory service, tips must be kept in good condition. The orifi ce end must be clean. See Figure 14-16. The tip surface must be clean and at a right angle to the orifi ce passages, so that the preheat fl ame is shaped and aimed properly. The sealing faces of the tip, (which contacts the torch body) must be clean and free from scratches, burrs, nicks, etc., or these joints may leak. Clean the tips as described in Chapter 13. Always store the extra tips in soft holders. A wooden block with holes drilled in it works well. See Chapter 13 for more detailed information about tip cleaning and care. 14.6 Cutting Steel with the Oxyfuel Gas Cutting Torch Metals that can be cut with the oxyfuel gas cutting torch are divided into two classes: Metals whose oxides (compound of oxygen and the metal) have a lower melting temperature than the metal itself. Metals whose oxides have a higher melting temperature than the metal itself. Figure 14-15. A cutting attachment screwed into place on a welding torch body. (CONCOA) Cutting attachment Torch body Figure 14-16. A typical cutting tip being cleaned.
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