Joints for Steel Water Pipe

or cement-mortar after completion of the welding is to brush on the lining through a 4-in. coupling which has been shop welded to the pipe close to each field joint. After the lining has been completed, the coupling is closed by a screwed plug. Figure 2 shows a "reinforced expanded bell" field joint, as used at Los Angeles for all pipe of 12-in. diameter or greater. This joint is cement calked in the same manner as a cast-iron pipe bell-and-spigot joint. It can be used for working pressures up to 200 psi. The advantages of this joint are its simplicity and low cost of laying in the field, and the fact that the inside lining remains intact and unaffected by the laying operations. Figure 3 shows a "bell-and-spigot for rubber gasket seal" joint, which is designed to give a very flexible, watertight, and low-cost field joint without any field welding or damage to the inside lining. It will permit deflections in alignment up to at least a 4-deg angle and longitudinal slippage of at