Terms Associates with Plastic Pipe and Fittings
Bell-and-Spigot Pipe
Pipe that has a bell (or enlargement, also called a hub) at one end of the pipe and a spigot (or smooth end, at the other end). The bell and spigot of two different pipes slide together to form a joint. Also called hub-and-spigot pipe.

Cellular Core Wall
Plastic pipe wall that is made of low-density, lightweight plastic containing entrained (trapped) air.

Chamfer
To bevel the edge of construction material to a 45-degree angle.

Chemically Inert
Does not react with other chemicals.

Compression Collar
A piece of hardware that uses compression force to connect sections of polyethylene piping.

Elastomeric
Rubberized. Made of an elastic substance such as a polyvinyl elastomeric.

Fusion Fitting
A fitting with a butt that has the same outside diameter and inside diameter as the pipe. It is usually joined to a pipe by heat.

Hydronic
A system that heats and cools by circulating water through a closed piping system.

Hydrostatic Pressure Test
To fill a pipe with water and bleed all air out from the highest and farthest points in the run.

Inside Diameter
The distance between the inner walls of a pipe; the standard measure of piping used in heating and plumbing.

Interference Fit
A fit that tightens as the pipe is pushed into the socket.

Outside Diameter
The distance between the walls of the pipe.

Pipe Riser Clamp
A vertical extension of pipe hanger that provides support for pipe and tubing.

Pressure Rating
The maximum pressure at which a component or system may be operated continuously.

Psi
Psi (pound-force per square inch) is a measurement of pressure.

Ring-Tight Gasket Fitting
A fitting with a rubber O-ring or gasket in the socket.

Schedule
A measurement that describes pipe wall thickness.

Size Dimension Ratio
A measurement of pipe size that relates pipe wall thickness to pipe diameter.

Solid Wall
A plastic pipe wall that does not contain trapped air.

Solvent Weld
A joint created by joining two pipes using solvent cement that softens the materials surface.

Thermoplastic Pipe
A pipe that can be repeatedly softened by heating, and hardened by cooling. When softened, thermoplastic pipe can be molded into desired shapes.

Thermosetting Pipe
A pipe that changes chemically when heated. Once hardened by heat or chemicals, it is hardened permanently.

Transition Fitting
A special fitting used to connect plastic pipe to a pipe of dissimilar material, as specified by applicable code.

Water Hammer
An extreme change in water pressure within a pipe that can cause a loud, banging sound and even damage the system.