The basic difference between a threaded union and threaded coupling is that threaded unions are made for joining and disassembling a part of a piping system such as a steam trap or control valve, etc for maintenance or replacement purpose. A coupling is used for joining pipe to pipe or pipe to a swedge.
Pipe Coupling and Unions are available in both types of forged fittings namely threaded and socket weld fittings. Pipe coupling are available in the form of Full Coupling, Half Coupling, and Reducing Coupling.
Couplings provide more robust joints in high-pressure applications whereas, in practice, unions are best suited to low-pressure applications.
More information of Pipe Unions:
- Materials: stainless steel, carbon steel, alloy steel, brass, etc.
- Connection Forms: threaded and socket welding connection.
- Manufacturing Standards: MSS SP 83, ASME B16.11.
- Types: there are different diameters and equal diameters of threaded unions.
- Product Link: SOCKET WELD COUPLING, SOCKET WELD UNION.
More information of Pipe Couplings:
- Materials: alloy steel, stainless steel, carbon steel, etc.
- Connection Methods: welding, socket, threaded connection, etc.
- Manufacturing Standards: ASME B16.11, BS 3799, GB/T14383, DIN2986, ASME B1.20.1, BS10241.
- Types: Full Coupling, Half Coupling, and Reducing Coupling.
- Product Link: THREADED COUPLING, THREADED UNION.
Pipe coupling is a lower-cost item and the union is a higher-cost item. When you need the ability to disassemble the piping for the removal of an item then you must use the higher-cost unions. When you are just joining pipe you would want to use the lowest cost item couplings.