What Is The Difference Between Pipe Coupling And Union?

The basic difference between a coupling and a union is that coupling is for joining pipe to pipe or pipe to a swedge and the union is made for joining and disassemble a part of a piping system (a steam trap or control valve, etc) for maintenance or replacement. The use of couplings or unions is not a code issue.

1. What is A Pipe Coupling?

A pipe coupling is a short piece of pipe used to connect two pipes and the pipe coupling connects two steel pipes through a threaded connection. The seal at the connection is a threaded seal. The disassembly should be disassembled from one end of the pipe in turn, mostly used for lengthening the pipeline.

  • Pipe coupling materials: carbon steel, stainless steel, alloy steel, PVC, plastic, etc.
  • Pipe coupling connection methods: threaded connection, welding, socket, etc.
  • Pipe coupling manufacturing standards: ASME B1.20.1, DIN2986, BS10241.
  • Pipe coupling manufacturing process: forging and casting (Forging refers to the use of steel ingots or round bars for heating and forging forming, and then processing threads on a lathe; Casting refers to the melting of steel ingots and pouring them into a fixed pipe hoop model, and then cooling them).
  • Pipe coupling applications: because of their convenient use, pipe couplings are widely used in civil construction, industry, agriculture, and other fields.

pipe coupling vs unionpipe coupling vs union
 

2. What Is A Pipe Union?

A pipe union is a commonly used pipe connector that can be easily installed and disassembled. It mainly consists of three parts: nut, cloud head, and flat connection. And the pipe union is generally used for there are front or back ends of valves, water meters, and other equipment in the pipeline, which is convenient for the disassembly and maintenance of this equipment.

  • Pipe union materials: threaded unions used in industry are generally made of metal with high-pressure resistance. The materials include carbon steel, stainless steel, alloy steel, brass, etc.; threaded unions used in daily life generally include PC, PVC, PE, etc.
  • Pipe union connection forms: socket welding and threaded connection. (Socket welding is to insert a steel pipe into a socket for welding. Therefore, it is called "socket "Swivel joint"; the threaded connection is to screw the steel pipe into the screw hole for connection. Therefore, it is called "threaded union". )
  • Pipe union main manufacturing standards: ASME B16.11, MSS SP 83.
  • Thread union definition: threaded union refers to a pipe connection with thread, which is the most common type of pipe fitting in industry and life. The threaded union makes the connection of the pipeline simpler and easier to disassemble and replace, which greatly saves the cost of the pipeline connection.
  • Threaded union type: there are equal diameters and different diameters of threaded unions.

pipe coupling vs unionpipe coupling vs union
 

3. Pipe Coupling VS Union

Both pipe couplings and pipe unions belong to pipe fittings.

The basic difference between a coupling and a union is that coupling is for joining pipe to pipe or pipe to a swedge and the union is made for joining and disassemble a part of a piping system (a steam trap or control valve, etc) for maintenance or replacement. The use of couplings or unions is not a code issue.

Couplings are pipe fittings in the pipeline. If the pipeline exceeds the length of a single pipe (such as 4m, 6m, etc.), a coupling should be used, which means that the coupling is purely to extend the pipeline; the union can be disassembled as a pipe fitting, that is, the things connected through the union can be removed and replaced, such as the valve side, the radiator side, etc., for maintenance and disassembly. And Pipe unions are generally used on threaded pipes and used on pipes with small pipe diameters. Larger pipe diameters are generally connected by means of flanges, etc., which are also easy to disassemble.

The pipe coupling has threaded coupling, butt welded coupling, and socket coupling, while the pipe union only has threaded union and socket union. Even the slip knot of the socket can be unscrewed with threads. With a union, there is no need to screw the pipe. If there is no threaded connection of the union, the pipe must be moved to disconnect the connection.

From the practical application point of view, the union is used on low-pressure occasions, while pipe coupling is used on high-pressure occasions. The union is a threaded connection, which is generally used in public engineering occasions less than 10kg.

Hebei Sanvo is one of the quality pipe fittings manufacturers and suppliers in China and exports a variety of threaded steel pipe fittings, including carbon steel pipe nipple, carbon steel pipe coupling, stainless steel pipe nipple, stainless steel pipe coupling, and stainless steel threaded pipe fittings. 

If you are interested in our pipeline products, please do not hesitate to contact us, we look forward to good news.

Send Your Message