Copyright Goodheart-Willcox Co., Inc. 330 Section 3 Plumbing System Design and Installation was applied. No bead or a partial bead may indicate in- complete bonding that could result in a leaking joint. The solvent cement will set up in two to five minutes and can be handled with care at that time. Allow 24 hours setting time before testing the pipe. 21.4.3 Supporting Plastic Pipe Horizontal runs of plastic pipe should be supported every 3′–4′ with metal or plastic hangers that are 3/4″ or more in width. Stacks should be set in concrete at their base and secured to the building frame in order to maintain alignment. Additional information about pipe supports is provided in Chapter 23. 21.5 Installing Copper Pipe and Fittings Copper DWV pipe measurements can often be taken shoulder-to-shoulder. However, face-to-face measure- ments are frequently more convenient. Appropri- ate allowances for fitting socket depth are shown in Figure 21-32. The laying lengths for common copper fittings are given in Figure 21-33. 21.5.1 Cutting Copper Pipe and Tubing Copper pipe and tubing should be cut with a tubing cutter, Figure 21-34. Slowly rotate the tubing cut- ter around the pipe. Tighten the cutter one-fourth to one-half turn with each revolution until the pipe is cut. Ream the cut end of the pipe to remove the burr pro- duced in cutting the pipe. See Figure 21-35. 21.5.2 Supporting Copper Pipe Horizontal runs of copper pipe should be supported every 4′–6′ with copper pipe hangers. Vertical runs of pipe should be secured to maintain alignment. Code Note IRC Note IRC Chapter 26, Section P2605, provides the requirements for supporting pipe. The distance between supports for horizontal pipe depends upon the type of material used to make the pipe and the diameter of the pipe. 21.6 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 21-37 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. Socket Allowances for Copper Fittings Pipe size (in) Engagement (in) 1 1 1/4 1 1/2 2 2 1/2 3 3 1/2 4 5 6 15/16 1 1 1/8 1 3/8 1 1/2 1 11/16 1 15/16 2 3/16 2 11/16 3 1/8 Goodheart-Willcox Publisher Figure 21-32. Make allowance for these socket depths when measuring copper piping. P R O C E D U R E Joining Copper Pipe Copper DWV pipe and fittings are joined by soldering. 1. Clean both the end of the pipe and the inside of the fitting socket. 2. Once the parts are clean, apply flux to prevent the copper from oxidizing too quickly when it is heated, Figure 21-36. 3. Assemble the parts and heat them with a soldering torch until they are hot enough to melt the lead-free solder that is used to make the joint. Excessive heating will burn away the flux and cause oxi- dization that will prevent the solder from bonding. Soldering is discussed in more detail in Chapter 11. Take care to avoid igniting the wood framing around solder joints. A shield made of fire resistant material is very helpful. It is also a good practice to have a fire extinguisher nearby, in case it is needed.