Installing Galvanized and Black Iron Pipe Galvanized iron pipe is seldom used for DWV systems. An exception is its use to run small diameter drains as a part of a cast iron DWV system. Black iron pipe is not approved for DWV piping. However, it is used for gas and compressed air. Figure 19-37 gives allowances for the engagement of threads into galvanized or black iron pipe fittings. These allowances must be added to all face-to- face measurements. Cutting and Threading Galvanized and Black Iron Pipe A pipe cutter, Figure 19-38, is the best tool for cutting galvanized and black iron pipe. It works In 1966, a critical shortage of copper in the U.S. halted construction of many large housing developments and spurred the introduction of plastic DWV pipe and fittings. Goodheart-Willcox Publisher Figure 19-34. Copper tubing is cut with light pressure on the cutting wheel. Goodheart-Willcox Publisher Figure 19-35. Ream the tubing to remove ridge left by cutting. A reamer blade is often built into the tubing cutter. Goodheart-Willcox Publisher Figure 19-36. Flux removes oxidation from copper tubing and prevents new oxidation from occurring during the soldering process. Goodheart-Willcox Publisher Figure 19-37. Dimensions in right-hand column are allowances to be added to face-to-face measurements of galvanized or black iron pipe. The allowance adjusts for the distance pipe is threaded into fitting. Distance Iron Pipe Is Turned into Standard Fittings Pipe size (in) Engagement (in) 1¼ 1½ 2 11/16 11/16 ¾ 2½ 3 3½ 15/16 1 11/16 Chapter 19 DWV Pipe and Fitting Installation 317 Copyright Goodheart-Willcox Co., Inc.