Coupling (piping)

For other uses, seeCoupling (disambiguation).

Inpipingandplumbing,acoupling(orcoupler) is a very short length ofpipeortube,with a socket at one or both ends that allows two pipes or tubes to be joined,welded(steel),brazedorsoldered(copper,brassetc.) together.

Pipe coupling (copper sweat)

Alternatively it is a short length ofpipewith twofemaleNational pipe threads(NPT) (in North American terms, a coupler is a double female while a nipple is double male) or two male or femaleBritish standard pipe threads.

If the two ends of a coupling are of different standards or joining methods, the coupling is called anadapter.Examples of adapters include one end BSP threaded with the other NPT threaded, and one end threaded with the other a plain socket for brazing.

A coupling whose ends use the same connection method but are of different sizes is called areducing couplingorreducer.An example is a 3/4 "NPT to 1/2" NPT coupling.

See also

• Closet flange
• Eccentric reducer
• Nipple (plumbing)
• Piping and plumbing fittings
• Reducer
• Street elbow

Further reading

• ASME B1.20.7 Hose Coupling Screw Threads, Inch. (Quote:The normal sequence of connections, in relation to the direction of flow, is from an externally threaded nipple into an internally threaded coupling)

External resources

• PDF illustrating assorted adapters