DWV Pipe and Fitting Installation CHAPTER 19 fittings must be placed accurately so fixtures can be hooked up easily during the finish stage. Procedures for completing layout and making modifications to the structure were discussed in Chapter 18. This chapter focuses on the actual installation of DWV piping systems. In the following section, techniques for measuring pipe are discussed. This will give you background for the following section that provides an overview of the DWV installation. Later sections of this chapter describe procedures for installing the various types of pipe and fittings typically used for DWV systems. Measuring Pipe Accurate measurements are critical to the success of every plumbing installation. It is often difficult, if not impossible, to measure directly the length of pipe required to join two fittings. Tech- niques that require knowledge of fitting allowances and the laying length of fittings must be used. This introduction to these methods will help you understand the remainder of this chapter. Measurements to determine the length of pipe are taken in one of three ways: Face-to-face. Shoulder-to-shoulder. Center-to-center. Figure 19-1 illustrates the three methods. The face-to-face method requires that the plumber know the fitting allowance for the type and size of fitting being installed. This information is provided with the procedures for installing each of the different types of pipe. Objectives This chapter describes the installation of drain/ waste/vent (DWV) systems. An overview of the process is presented first, followed by a description of the techniques for cutting and joining each of the kinds of pipe and fittings. After studying this chapter, you will be able to: Describe proper procedures for locating and installing DWV piping systems. Use the prescribed techniques for working with plastic, copper, galvanized iron, black iron, and cast-iron DWV materials. Compare and use the three methods of measuring pipe length between fittings. Describe or demonstrate methods for testing and inspecting completed DWV systems. Technical Terms Face-to-face Shoulder-to-shoulder Center-to-center Laying length Flashing Oakum Joint runner In the first rough stage, the building sewer and water supply are installed. These are pipes that extend from the water and sewer mains to the inside of the building. The second rough stage is the installation of all plumbing that will be enclosed in the walls or that must be installed before the walls are finished. This includes DWV, hot and cold water supply piping, bathtubs, and shower bases. The second rough stage of DWV installation is critical because the correct slope must be main- tained in horizontal runs of pipe. Also, pipes and 297 Copyright Goodheart-Willcox Co., Inc.
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