Fittings are used in pipe systems to connect straight pipe or tubing sections, to adapt to different sizes or shapes, and to regulate fluid flow, for example. Fittings, especially uncommon types, can be expensive, and require time, materials, and tools to install, so they are a non-trivial part of piping and plumbing systems. Valves are technically fittings, but are usually discussed separately. The bodies of fittings for pipe and tubing are most often of the same base material as the pipe or tubing being connected, for example, copper, steel, brass, polyvinyl chloride (PVC), or chlorinated polyvinyl chloride (CPVC). However, any material that is allowed by code may be used, but must be compatible with the other materials in the system, the fluids being transported, and the temperatures and pressures inside and outside of the system. There are many different kinds of pipe fittings: elbows, reducers, tees, cross, caps, plug, nipples, barbs, flanges, threaded pipes, union, coupling, etc. On B2BManufactures.com, Pipe Fittings Manufacturers & suppliers listings in full models and specifications. All pipe fittings made by leading Chinese pipe and fitting suppliers. Global buyers could send inquires online.
source: Wikipedia: the free encyclopedia