Standard Plumbing Fittings

Among the varied applications of plumbing pipes, pipe fittings appear in a dependable set of shapes and they join by relatively few connection methods. Whether you are working with water-supply pipe, drainpipe, metal pipe or plastic pipe, you will encounter pipes with familiar angles, profiles and installation requirements. An understanding of standard fittings' functions and terminology helps you communicate with plumbing professionals, understand installation instructions and purchase plumbing materials.

Basic Bends and Shapes

Plumbers frequently use bends to route piping systems. Plumbers call short, tight bends, elbows and long, arching bends, sweeps. The most common angles of bends are 90 degrees and 45 degrees, respectively called nineties and forty-fives. Bends and other fittings may slip either over a pipe's ends or inside an adjacent fitting. Fittings that slip inside an adjacent fitting are called street fittings, such as a "street 90." Common fitting shapes include the Tee and Wye, which approximate the shapes of their namesake letters. Fittings that join pipes in a straight line are called couplings and two-part, threaded couplings are called unions.

Traps and Vents

Traps and vents are special features of drain, waste and vent plumbing systems. Traps are the P-shaped drain assemblies located beneath sinks, showers and tubs. Plumbers construct vent piping from the same materials as drain piping, but run the vents through the roof instead of to the sewer. Traps literally trap water to form a seal between the sewer and a fixture's drain opening. Vents give sewer gases an escape and allow air to enter the drain system. Air admission maintains drain system pressure and prevents traps from emptying.

Valves

Plumbers install valves throughout water supply systems to isolate appliances and portions of the piping in case of repair. Common residential valves include ball valves, gate valves and globe valves. The valves' names generally refer to the internal mechanisms that stem the flow of liquids. Valves are available with both plastic and metal bodies and connect to standard-size plumbing pipes. Garden hose valves are a common exterior valve. Alternative names for hose valves include spigots and hose cocks.

Connection Methods

Residential plumbing fittings and pipes usually connect via mechanical means, soldering or solvent welding. The most familiar mechanical connection method is threading and threaded pipes and fittings have corresponding grooves that "screw-in" to one another. Alternative mechanical methods include roll-grooving and push-fittings. Soldering usually applies to copper water supply lines. Plumbers heat copper fittings and pipes with a torch and melt a filler metal into the joint. The term solvent welding refers to "gluing" plastic fittings and pipes with a chemical solvent.

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