Coupling fittings, adapters, plugs, caps and unions are all designed to terminate or extend pipe runs, according to the Keidel Supply Co. Elbows are employed in plumbing to change the direction of water flow. Tees, side-inlet elbows, crosses and wyes are manufactured to connect two or more pipes together. Reducers, couplings, adapters and bushings are employed to change the size of a pipe.
According to the Pipe Fittings & Flanges website, the most widely used types of materials in the construction of plumbing fittings include aluminum, steel, cast iron, brass, copper and PVC (polyvinyl chloride) plastic. Each material offers its benefits and considerations. Cast iron fittings are often employed in a building's sanitary, waste and drainage system. Brass fittings are very versatile and have applications outside of plumbing in moving chemicals and gases.
Different fabrication materials offer different benefits. Aluminum and copper fittings are relatively lightweight and very resistant to corrosion. The largest benefit associated with cast iron fittings is that they are highly resistant to abrasion. Fittings made out of steel and brass are often employed for their durability and strength. PVC fittings are the cheapest type of fittings on the market, and they are considered to be easy to use, according to Builder's Websource.
Only proper fittings should only be applied to the pipes in a plumbing system. For example, it is only recommended that pipe fittings made of copper be applied to copper piping. Only PVC pipe fittings should be employed to join PVC pipes. Some metals are prone to corrosion; steel fittings for plumbing should be galvanized to discourage rusting. According to Savvy Cafe, copper pipes and fittings can leave the water they move with a slight "metallic" taste.
Plumbing fittings are available in sizes that to fit into or over most pipe diameters. Plumbing fittings can be found in metric as well as standard measurements, according to Pipe & Tube Fittings. Metric plumbing fittings are available in sizes ranging from between 10 mm and 1,000 mm in diameter. Standard plumbing fitting sizes typically range in diameter from 1/8-inch to 36-inch.