What Is API 5CT Standard for Oil Casing & Tubing

API 5CT is the core international standard for OCTG casing and tubing. Learn its key requirements for steel grades, threads and inspection.

API 5CT is the most widely‑recognized international standard for oil casing, tubing and couplings used in oil and gas drilling projects.

It covers steel grade classification, thread dimension, heat‑treatment requirements, mechanical property testing and non‑destructive inspection rules.

Common steel grades include K55, N80‑1, N80Q, L80‑1, L80‑13Cr etc. Different grades are designed for different down‑hole environments.

Products manufactured strictly in accordance with API 5CT can guarantee safety and stability for oil‑well operation.

Our factory implements full‑range production and testing following API 5CT specification for all OCTG goods.