A tubing coupling joins adjacent tubing joints and must maintain mechanical continuity and the required pressure integrity through installation and service. Its dimensions, material and thread form must match the tubing and connection designation.
Thread profile, clearance, sealing mechanism, make-up requirements and compatibility with handling equipment should be reviewed together. API connections and proprietary premium connections are not interchangeable simply because the pipe size is the same.
Coupling grade, heat treatment, hardness and surface condition should suit the tubing and the well environment. Sour or corrosive service may introduce additional material, testing and traceability requirements.
Typical controls include dimensional verification, thread gauging, visual inspection, surface examination where specified, cleanliness, protectors and traceability to the applicable records.