Casing and tubing couplings are short lengths of pipes applied to connect two joints of casing and tubing. They are painted different color codes on their external surface to indicate their grades.Casing coupling and tubing coupling are manufactured according to API 5CT and 5B specifications.

API Casing Coupling
API Tubing Coupling
Pup Joints are used to adjust the height of full length tubing or casing strings. They are also used to adjust the depth of downhole tools.
Casing Pup Joint
Tubing Pup Joint

Coupling

API Casing Coupling
Standard:API 5CT&5B
Size (Pipe OD) (in):4-1/2, 5, 5-1/2, 6-5/8, 7, 7-5/8, 8-5/8, 9-5/8, 10-3/4, 11-3/4, 13-3/8, 16, 18-5/8, 20
Threading types:Short Round-Thread Casing (STC),Long Round-Thread Casing (LC),Buttress Thread Casing (BC)
Grade:H-40, J-55, K-55, C-75, L-80, N-80, C-95, AS-95, P-110, L80-13CR

API Tubing Coupling
Standard:API 5CT&5B
Size (Pipe OD) (in):1.9”-4-1/2”
Upset:Non Upset,External Upset
Grade:J-55, C-75, L-80, N-80, C-95, P-110
Option:Electro-zinc plated, Phosphorised
Threading types:API 5B – Last Edition or Premium, VAM Premium, EUE, NUE, special seal, metal-to-metal seal and VAGT

Pup joint
Casing Pup Joint
Size：4-1/2 ~ 20 in (114.3 ~ 508 mm) nominal size OD
Weight：Standard or Heavy Wall
Length：2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20 ft (with other lengths available upon request)
Grade：H40, J55, K55, L80, N80/Q, C90, T95, P110, Q125
Threading types：BTC, STC, LTC
Standard：API 5CT, API 5B
Uses：used to adjust the height of full length tubing or casing strings.

Tubing Pup Joint
Size：1.05 ~ 4-1/2 in (26.67 ~ 114.3 mm) nominal size OD
Weight：Standard or Heavy Wall
Length：2, 3, 4, 5, 6, 8, 10, 12 ft (with other lengths available upon request)
Grade：H40, J55, L80, N80/Q, C90, T95, P110
Threading types：EUE, NUE
Standard：API 5CT, API 5B
Uses：used to adjust the height of full length tubing or casing strings.

API Spec 5CT–Specification 5CT/ISO 11960, Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells
API 5B–This specification covers dimensions, tolerances, and marking requirements for API threads and the gauges that control the acceptance criteria for the threads. Thread element gauges, instruments, and requirements for the inspection of threads for line pipe, round thread casing, round thread tubing, and buttress casing connections are included