Copyright Goodheart-Willcox Co., Inc. 334 Section 3 Plumbing System Design and Installation 21.7.3 Joining Cast-Iron Pipe No-hub cast-iron pipe is joined with a neoprene gasket and a stainless steel clamp. Slip the neoprene gasket onto the pipe, then position the clamp over the gasket. Finally, tighten both clamp screws to 60 inch-pounds. A torque wrench works best. Bell and spigot cast-iron pipe is joined with neo- prene compression gaskets or lead and oakum. Neo- prene compression gaskets, Figure 21-47, are installed as the pipe is assembled. Spraying with silicone lubri- cant makes the assembly easier. Code Note IRC Note IRC Chapter 25, Section P2503, describes the requirements for plumbing inspection. Inspection of the rough-in plumbing must be completed before pipe is covered or otherwise concealed. 21.7.4 Supporting Cast-Iron Pipe Cast-iron pipe, because of its weight, must be well sup- ported while joints are being made. Permanent supports must be installed before the first rough is completed. These supports should be placed at every joint on horizontal runs unless the distance between joints is less than 4′. Code typically requires supporting hori- zontal cast iron pipe every 5′. Use special hangers for this purpose. Vertical runs of cast-iron pipe can be at- tached to the building structure with vertical pipe brackets or pipe straps. Riser clamps should support the weight of cast-iron pipe at each floor level. Neoprene compression gasket A B E.I. duPont de Nemours & Co. The Ridge Tool Co. Figure 21-47. Joining pipe with a compression gasket. A—Special gaskets can be used in place of oakum and lead. B—A pipe assembly tool will force the compression gasket into the joint. A B The Ridge Tool Co., Wheeler Mfg. Division of Rex International USA, Inc. Figure 21-46. Chain-type cutters for use on cast-iron pipe. A—Cutter with a compound lever mechanism. B—Cutter with a hydraulic cylinder.