API 5CT Casing and Tubing Specification

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Coating and Treating Specialty Services in Texas

API 5CT is standard technical specifications for steel casing and tubing pipes used for oil wells in petroleum and natural gas industries.

Besides casing and tubing, it also includes pup joints, coupling stock, coupling material, and accessory materials, and establishes requirements for three product specification levels (PSL-1, PSL-2, and PSL-3). The requirements for PSL-1 are the basis of this standard.

Common Grades

• J55/K55
• N80/N80Q/L80
• C90
• R95/T95
• P110/C110
• Q125


API 5CT is applicable to following connections which complied with API SPEC 5B:
• SC: Short round thread casing
• LC: Long ound thread casing
• BC: Buttress thread casing
• NU: Non-upset tubing
• EU: External upset tubing
• IJ: Integral tubing connections

4 Groups of Grade

• Group 1: All casing and tubing in Grades with H, J, K, N and R
• Group 2: All casing and tubing in Grades with C, L, M and T
• Group 3: All casing and tubing in Grade P
• Group 4: All casing in Grade Q

View more information for API Couplings and Connections.



According to API 5CT standard, steel material used for making the pipe billet supplied shall be grain refining treatment. This steel shall contain one or more grain refining elements, such as a certain amount of aluminum, niobium, vanadium or titanium, so that the austenite grains of the steel Grain refinement.

• Pipes supplied shall be manufactured in seamless type or EW type.
• Couplings, coupling stock and coupling materials shall be in seamless.
• Cold drawn tubing pipe shall be properly heat treated, otherwise is not acceptable.
• Casing and tubing attachment materials shall be seamless pipe, unless other type stated on the order.

Casing and Tubing is a kind of OCTG pipe

Lincoln Manufacturing

Lincoln Manufacturing

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