Various types of joints and connections used in waste drainage systems are described below.

types of joints (fig. 8-17) are used to connect cast-iron soil pipes (CISP) and fittings. In lead and oakum joints, oakum (made of hemp impregnated with bituminous compound and loosely twisted or spun into a rope or yarn) is packed into the hub completely around the joint, and melted lead is poured over it (fig. 8-17, view A). In compression joints, an assembly tool is used to force the spigot end of the pipe or fitting into the lubricated gasket inside the hub (fig. 8-17, view B). A no-hub joint uses a gasket on the end of one pipe and a stainless steel shield and clamp assembly on the end of the other pipe (fig. 8-17, view C).

MORTAR OR BITUMINOUS JOINTS. This type of joint is common to vitrified clay and concrete pipes and fittings. Mortar joints may be made of grout (a mixture of cement, sand, and water).

The use of SPEED SEAL JOINTS (rubber rings) in joining vitrified clay pipe has become widespread. Speed seal joints eliminate the use of oakum and mortar joints for sewer mains. This type of seal is made a part of the vitrified pipe joint when manufactured. It is made of polyvinyl chloride and is called a plastisol joint connection.

A trap is a device that catches and holds a quantity of water, thus forming a seal that prevents the gases resulting from sewage decomposition from entering the building through the pipe. A number of different types of traps are available; however, the trap mainly used with plumbing fixtures is the P-TRAP (fig. 8-18). It comes 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 wrought iron, copper, other metal alloys, and plastic.

Traps are commonly installed on fixtures, such as lavatories, sinks, and urinals. At times, the P-trap may also be suitable in shower baths and other installations that do not require wasting of large amounts of water.