Figure 8-17.-Various joints currently used to connect CISPand fittings.Joints and ConnectionsVarious types of joints and connectionsused in waste drainage systems are describedbelow.LEAD AND OAKUM JOINT, COMPRES-SION JOINT, AND NO-HUB JOINT.— Thesetypes of joints (fig. 8-17) are used to connectcast-ironsoilpipes(CISP)andfittings.In leadand oakum joints, oakum (made of hemp im-pregnated with bituminous compound and looselytwisted or spun into a rope or yarn) is packedinto the hub completely around the joint, andmelted lead is poured over it (fig. 8-17, view A).In compression joints, an assembly tool is usedto force the spigot end of the pipe or fitting intothe lubricated gasket inside the hub (fig. 8-17, viewB). A no-hub joint uses a gasket on the end ofone pipe and a stainless steel shield and clampassembly on the end of the other pipe (fig. 8-17,view C).MORTAR OR BITUMINOUS JOINTS.—This type of joint is common to vitrifiedclayandconcretepipesandfittings.Mortar joints may bemade of grout (a mixture of cement, sand, andwater).The use of SPEED SEAL JOINTS (rubberrings) in joining vitrified clay pipe has becomewidespread. Speed seal joints eliminate the use ofoakum and mortar joints for sewer mains. Thistype of seal is made a part of the vitrified pipejoint when manufactured. It is made of polyvinylchloride and is called a plastisol joint connection.TrapsA trap is a device that catches and holds aquantity of water, thus forming a seal thatprevents the gases resulting from sewage decom-position from entering the building through thepipe. A number of different types of traps areavailable; however, the trap mainly used withplumbing fixtures is the P-TRAP (fig. 8-18). Itcomes in sizes from 1 1/4 in. to 6 in. in diameter.P-traps are usually made of nickel or chrome-plated brass, malleable galvanized or wroughtiron, copper, other metal alloys, and plastic.Figure 8-18.-P-traps.8-14
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