This type of coupling is used to connect pipes made of Stainless steel or Carbon steel.
As their name indicates, compression couplings form a tight seal by applying a compression force to pipes and to the pipe coupling. The coupling is compressed against the pipe with sufficient force to eliminate all the space remaining in the joint, thus preventing fluid leaks.
The compression coupling consists of an external “compression nut” and an internal “ring” or “olive”. When the nut is tightened it becomes fixed on the olive and makes it take the shape of the circumference of the pipe. The shape and the material of the olives can vary according to the pipe material. In order to function correctly, the olive must be the right way round. The olive is normally placed so that the longer inclined side is furthest away from the nut.
The couplings produced by some manufacturers only have a single olive. On our sites we use “Swagelok” connections with 2 rings (front and rear).
All these couplings are those most commonly used. We will see in the next chapter how to connect our instrumentation tubes to these couplings. The ring or olive couplings are the most reliable and the most solid I have met.
There are also plastic quick-connect couplings. As far as maintenance is concerned, they are not the best equipment since they can break in your hands because they very quickly deteriorate due to heat or to the sun’s rays.
Straight couplings
Male union
Female union
Male end fitting
Equal union
Piping penetration
The “piping penetration” coupling is very practical when you want to get air into a box (e.g. distributor box).
45° elbow couplings
90° elbow couplings
Union elbow
Male elbow coupling
Female elbow coupling
Tees
Union Tee
Male Tee
Female Tee
