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A Short Article on Coupling as Pipe Fitting

Characteristics, Benefits and Uses of Stainless Steel Forged Fittings

A Pipe Coupling, utilized in pipes or plumbing, is a very short pipe or tube length at one or both ends with either socket or female pipe thread that enables two pipes or tubes of similar or different sizes to be connected together. Couplings are pipe fittings that help to extend or stop pipe runs. These fittings are often used to adjust the size of the tubing. It is often used to fix a cracked or leaking pipe. These coupling are available in various materials like carbon steel, duplex steel, titanium, copper nickel, monel, Inconel, however stainless steel coupling are most wide used.

Most pipe installations require the joining or cutting of several lengths of pipe to allow changes of direction and obstacle crossing. This involves a very quick process of connecting the parts of the pipe while maintaining the integrity of the pipes in the system. A pipe coupling is a pipe fitting that is used to connect two or more pipes in such a way as to maintain continuity between them.

Usually, the body of a pipe coupling is produced of the same or similar material as that of the pipes which it joins. Based on the amount of movement the pipe is exposed to, they may be rigid or flexible, and may be permanent or temporary. The internal diameter of a pipe coupling can be expanded or shortened to join pipes of different sizes, be T or cross-shaped to connect more than two pipes, or angled to form bends. Pipe couplings might also include peripheral characteristics or equipment such as openings, flow meters, or valves for inspection.

Categories of Pipe Couplings

Couplings under the scope of pipe fittings can be divided into two main categories.

  • Permanent Coupling
  • Removable Coupling

Permanent Coupling

Permanent pipe couplings usually utilize welding or brazing in the case of steel or copper pipes or adhesives in the case of PVC pipes. Such permanent connections, if correctly designed, provide outstanding stability and sealing properties where no potential improvements in the pipe are possibly predicted.

Removable Coupling

Removable pipe couplings are most frequently of a threaded nature that requires them to be screwed onto the pipes to be connected. The simplest of these is the basic segment of the pipe slightly wider than the pipes to be connected and cut by the inner thread. The ends of the pipes are often threaded, and the coupling is easily sealed with a hemp or seal tape and screwed into both sides.

Types of Pipe Couplings

  • Full Coupling
  • Half Coupling
  • Reducing Coupling
  • Compression Coupling
  • Slip Coupling / Repair Coupling

Full Coupling

Full Coupling is utilized to connect small bore pipes. It used to connect pipe to pipe or pipe to swage or nipple. It can be threaded or socket ends types. These couplings are available in various materials but Stainless Steel Full Coupling are most widely used.

The socket weld of the full coupling is used to connect small-bore plain end pipes where the socket weld is needed for the specification of the pipe. A threaded full coupling is used to connect small bore pipes with threaded ends. When the two ends of the coupling are distinct (e.g. one threaded BSP and one threaded NPT), it is generally referred to as the adapter.

Half Coupling

Half Coupling is utilized to connect small bore branching from a vessel or large bore pipe. It can be either threaded or socket type. It has a socket or thread end on only single side.

A socket weld half coupling can be directly welded to a large bore pipe, to make a branch connection. It is used to take a small bore pipe branch-off from a large bore pipe where the pipe spec requirement is socket weld in small bore size. A threaded half coupling only has one thread end and another end of the coupling should be butt welding end with either a plain end or a bevel end.