What Is an API 5CT Coupling
An API 5CT coupling is used to connect two threaded oil casing or tubing joints and is a cylindrical body featuring internal threads of the same grade and type as the oil casing or tubing. It provides the mechanical connection and sealing interface of the string, and its dimensions and threads are standardized per API 5CT and API 5B.
Usage Instructions
Before use, verify that the thread types on both ends match the design specifications of the components to be connected on site. Clean the threads and visually inspect the entire circumference for defects such as dents, cracks, or foreign matter. Evenly apply API-grade thread compound specifically designed for oil casing and tubing to the threads on both ends, then hand-tighten the mating threads by manual rotation. Using a torque-indicating tightening device, rotate to tighten to the API-standard specified torque value to prevent leakage and connection failure.
Specification Range
Tubing couplings range from 1.9 to 4-1/2 inches and casing couplings from 4-1/2 to 13-3/8 inches. Thread types include NUE, EUE, STC, LTC, and BTC, and grades include J55, L80, N80, and P110, with the full range covering J55, K55, N80-1, N80-Q, L80-1, C90, C95, T95, P110, and Q125 per API 5CT and 5B PSL1 and PSL2.
Surface Treatment and Color Coding
The standard surface treatment is phosphating, which improves thread lubrication and anti-galling performance. Color coding identifies the grade: J55 is green, L80 is red with brown stripes, and N80 uses its specified band colors, preventing mixing of grades at the well site.
Quality and Handling
Couplings are inspected for thread form, dimensions, and surface condition, and the thread compound is applied evenly without contaminating the coupling interior. Protectors are kept on until make-up to prevent thread damage.
Frequently Asked Questions
Q: What is an API 5CT coupling?
A: A cylindrical connector with internal threads joining two casing or tubing joints.
Q: What must be verified before make-up?
A: Thread type match, cleanliness, and absence of defects.
Q: What thread types are available?
A: NUE, EUE, STC, LTC, and BTC.
Q: What grades are covered?
A: J55, K55, N80, L80, C90, C95, T95, P110, and Q125.
Q: Why is thread compound used?
A: It lubricates the threads and provides the sealing medium for API connections.
Q: What is the standard surface treatment?
A: Phosphating for lubrication and anti-galling.
For API 5CT couplings quotations with grade, thread, and size requirements, contact our sales team.
