The difference between a coupling and a union is that a coupling is for joining pipe to pipe or pipe to a swedge, while a union is for joining and disassembling components of a piping system, such as a steam trap or control valve, 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 threaded. The disassembly should begin at one end, typically used for lengthening the pipeline.
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Materials
Carbon steel, stainless steel, alloy steel, PVC, and plastic, among others.
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Connection methods
Threaded connections, welding, sockets, and other related components are essential in various mechanical and structural applications.
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Manufacturing standards
ASME B1.20.1, DIN2986, BS10241.
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Manufacturing process
Forging heats steel ingots or bars to shape them and process threads on a lathe while casting melts steel ingots and pours the molten metal into a fixed mold to cool.
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Application
Because of their convenient use, pipe couplings are popular in civil construction, industry, agriculture, and other fields.
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. The pipe union is used at the ends of valves, water meters, and other equipment in the pipeline and is convenient for disassembly and maintenance.
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Material
Threaded unions are in industries that require metals with high-pressure resistance. Materials such as carbon steel, stainless steel, alloy steel, and brass are commonly used, along with plastics like PVC, PE, and others.
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Connection forms
Socket welding and threaded connection. (Socket welding is to insert a steel pipe into a socket for welding. Therefore, it is called a "socket "Or swivel joint"; the threaded connection is to screw the steel pipe into the screw hole for connection. Therefore, it is called a "threaded union")
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Manufacturing standards
ASME B16.11, MSS SP 83.
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Definition
Threaded union refers to a pipe connection with thread, the most common type of pipe fitting in industry and life. The threaded union simplifies pipeline connections, allowing for easier and more cost-effective disassembly and replacement.
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Type
There are equal diameters and different diameters of threaded unions.
3. Pipe Coupling VS Union
Both pipe couplings and pipe unions belong to pipe fittings.
The fundamental difference between a coupling and a union lies in their functions: a coupling connects pipe to pipe or pipe to a swedge, while a union joins and disassembles components of a piping system, such as a steam trap or control valve, for maintenance or replacement. The use of couplings or unions is not a code issue.
Couplings are pipe fittings in the pipeline. Should use coupling when the pipeline exceeds the length of a single pipe (such as 4m, 6m, etc.), which means that the coupling is purely to extend the pipeline; the union as a pipe fitting disassembles that is, and the things connected through the union can be removed and replaced, such as the valve side, the radiator side, etc., for maintenance and disassembly. Pipe unions are generally on threaded pipes and pipes with small pipe diameters. For disassembling easily to larger pipe diameters are connected using flanges, etc.
The pipe coupling has threaded coupling, butt welded coupling, and socket coupling, while the pipe union only has threaded union and socket union. The socket slip knot must have threads to screw down; with a union, there is no need to screw the pipe. If the union unthreads, move the pipe to disconnect the connection.
From the practical application point of view, the union is used on low-pressure occasions, while pipe coupling is suitable for high-pressure occasions. The union is a threaded connection generally used in public engineering placement of less than 10kg.
4. Advantages and Disadvantages
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Pipe couplings have higher durability and can be used in severe environments in the long term due to their high-quality steel or more durable materials. With simple design and installation convenience, it can connect two pipes quickly. Good seal in joint to avoid leakage of fluid or gas. They can connect diverse sizes or types of tubes to make the system more flexible. However, due to the strong connection with the thread, it is hard to disassemble a portion of the couplings, particularly in high-pressure environments.
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Unions disassemble easily, making maintenance and part replacement convenient. The connection method can be selected based on your needs, providing greater flexibility. However, it is less robust when subjected to high pressure or strong vibrations than some fixed connection types. With repeated disassemblies over time, it is likely to become worn and less efficient, making it crucial to handle it with care to maintain its performance.
5. About us
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 nipples, carbon steel pipe coupling, stainless steel pipe nipples, 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, and we look forward to good news.