Product: Casing and Tubing Coupling, Casing Coupling, Tubing Coupling
Application: Used for connecting 2 joints of tubing or casing
Size: Tubing Coupling : 1.9'' - 4-1/2''
Casing Coupling: 4-1/2'' - 13-3/8''
Pipe Standard: API 5CT and 5B PSL1/PSL2 J55, K55, N80-1, N80-Q, API 5CT and 5B L80-1, C90, C95, T95, P110, Q125
Surface: Whole Phosphating or inside phosphating and outside coating
Thread: NUE, EUE, STC, LTC, BTC etc
About Tubing Coupling
Normally tubing coupling OD maximum is 4 1/2”, as the tubing pipe is applied for the drilling activities (Inside the tubing is the sucker rod to drill/pump the oil), couplings type is more various and rigorous than casing, mostly used is thicken type upset coupling (Internal upset and external upset), for short is EUE coupling, it is the most favorable in tubing connections. Tubing with EU end (EUE) coupling connection also called UPTBG. Because of the end of the tubing is thickened (upset), the connecting stress is better than buttress coupling.
Buttress coupling is another type used for tubing connections. It has the same thickness as the pipe body, called NU end (NUE) tubing or TBG.
Features
The oil tubing coupling can solve the problem of fatigue fracture in the existing coupling due to stress concentration. Oil tubing end is connected to the inside wall of the coupling in a tapered thread. The coupling body end and oil tubing are connected with same thread pitch flat thread. The coupling is not easy to produce fatigue fracture, and has good connection effect. It can prevent the accident of oil well pipe string break effectively.
About Casing Coupling
Casing coupling is for the dimensions more than 4 1/2 inch. Differently than tubing coupling is, casing coupling normally does not need to be thickened (Non-upset), which means no upset casing coupling, so it has following types:
• BTC: Buttress coupling
• LTC: Long buttress coupling
• STC: Short buttress coupling
All three types has same thickness of the casing pipe body, just have different lengths.
The oil casing coupling is a necessary piece used to connect two casings. The coupling manufacturing method is the same as seamless pipe. The steel pipe ends have internal threads to connect with the upper and lower casing. To ensure joint tightness, the precision of the screw thread is strictly required.
Seamless and ERW Casing
API 5CT
It specifies technical delivery requirements for casing, tubing, pup joints, coupling stock and accessories, and defines three product specification levels: PSL‑1, PSL‑2 and PSL‑3. PSL‑1 is the basic requirement; supplementary rules for PSL‑2/PSL‑3 (excluding special steel grades) are listed in Annex H. The standard also applies to non‑API connected pipes, excluding threading regulations.
API 5B
This standard governs the threading, gauging and inspection of casing, tubing and line pipe threads. It specifies thread gauge dimensions, marking rules and inspection methods for various thread types. It applies to relevant API products and covers inspection of thread taper, lead, height and angle. Dimension data without tolerances are for connection design only, not for product acceptance testing.
