API Coupling and Threads for Casing and Tubing

 

As we know steel pipe coupling is a short pipe or tube that with threads on both ends, used to connect pipelines. So It is a kind of pipe fittings that with threaded connection, the advantage is easy for pipeline maintenance or to replace the broken pipe

CANGZHOU WILSON PIPELINE manufacture of  flange fittings&pipes

What is API coupling used for?

To be simple, it is the internally threaded cylinder for joining two lengths of threaded pipe.

With this purpose, API 5CT standard coupling plays an important feature in connecting casing and tubing line pipes. On the contrary, the biggest different with general steel pipe coupling is: API coupling manufacturing processes is more rigorous, requires a precisely control in the different processes as blew listed.

Raw material selection
Mechanical test including tensile strength
Impact test
Chemical properties control
Sulfide stress cracking test (for Material grades in C90 or T95)
Size tolerances, OD, Wall Thickness, Length and Straightness
Threads control, threads quantity per inch, threads angle etc (Premium threads option will be more rigorous)
Heat treatment
Additional markings
Material certification
Product Specification Level (PSL-2 or PSL-3)

API coupling specification

As we told, one of the important figure of API coupling, that it shall be made of seamless, another is the same grade as the casing or tubing pipe body, and these materials are used for manufacturing the blank coupling.

Coupling should be processed from coupling blanks or from coupling stock, including manufactured in hot forging. (Except Grade C110 and Q125 couplings shall not be in hot forging. These two grades material are typically different from other grades, so if you are purchasing couplings in this grades, should pay more attention to read regulations in API 5CT spec.)

API Coupling raw material type

Coupling raw material called as or divided to:
• Coupling stock
• Coupling material
• Coupling blanks
• Accessory material
All of these could be taken as the unthreaded material used to produce an individual coupling.