Variations between Casing Coupling and Tubing Coupling

You will find couplings for casing pipe and couplings for tubing, the part is identical that for connecting the pipe one another. However, still there are several variations backward and forward.

Casing coupling

Casing coupling is perfect for the scale greater than 4 1/2 inch. Differently than tubing coupling is, casing coupling normally doesn’t need to be thickened (Non-upset), meaning no upset casing coupling, therefore it has following types:

• BTC: Buttress coupling

• LTC: Lengthy buttress coupling

• STC: Short buttress coupling

The 3 types has same thickness from the casing pipe body, simply have different lengths.

The oil casing coupling is really a necessary piece accustomed to connect the 2 casing. The coupling manufacturing method is equivalent to seamless pipe. The steel pipe ends with internal thread for connecting using the lower and upper casing. To guarantee the joint tightness, the truth of screw thread is just needed.

Tubing coupling

Normally tubing coupling OD maximum is 4 1/2”, because the tubing pipe is used for that drilling activities (Within the tubing may be the sucker fishing rod to drill/pump the oil), couplings type is much more various and rigorous than casing, mostly used is thicken type upset coupling (Internal upset and exterior upset), for brief is EUE coupling, it’s the best in tubing connections. Tubing with EU finish (EUE) coupling connection also known as UPTBG. Due to the finish from the tubing is thickened (upset), the connecting stress is preferable to buttress coupling.

Buttress coupling another kind employed for tubing connections, her same thickness from the pipe body, known as NU finish (NUE)tubing or TBG.

Features

The oil tubing coupling can solve the issue of fatigue fracture within the existing coupling because of stress concentration. Oil tubing finish is attached to the inside wall from the coupling inside a tapered thread. The coupling body finish and oil tubing are associated with same thread pitch flat thread. The coupling is difficult to create fatigue fracture , and it has good connection effect. It may avoid the accident of oil well pipe string break effectively.