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API Spec 5CT Casing pipe

API Spec 5CT Casing pipe

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.

Standard: API SPEC 5CT

API 5CT pipe Size (mm):
  • Outer Dimensions: 6.0mm – 219.0mm
  • Wall Thickness: 1.0mm – 30 mm
  • Length: max 12000mm

Application: gas, water and oil transportation in both oil and natural gas .

The main steel grade of API 5CT:
  • API 5CT J55
  • API 5CT K55
  • API 5CT N80
  • API 5CT L80
  • API 5CT P110

Packing: Bare/bundles/crates/crate protection at the both sides of tubes or as per customers’ requirements .

This International Standard is applicable to the following connections in accordance with ISO 10422 or API Spec 5B:

  • short round thread casing (STC);
  • long round thread casing (LC);
  • buttress thread casing (BC);
  • extreme-line casing (XC);
  • non-upset tubing (NU);
  • external upset tubing (EU);
  • integral joint tubing (IJ).

For such connections, this International Standard specifies the technical delivery conditions for couplings and thread protection.

For pipes covered by this International Standard, the sizes, masses, wall thicknesses, grades and applicable end finishes are defined.

This International Standard may also be applied to tubulars with connections not covered by ISO/API standards.

Chemical Composition of API 5CT
Grade C≤ Si≤ Mn≤ P≤ S≤ Cr≤ Ni≤ Cu≤ Mo≤ V≤ Als≤
J55 0.34-0.39 0.20-0.35 1.25-1.50 0.020 0.015 0.15 0.20 0.20 / / 0.020
K55 0.34-0.39 0.20-0.35 1.25-1.50 0.020 0.015 0.15 0.20 0.20 / / 0.020
N80 0.34-0.38 0.20-0.35 1.45-1.70 0.020 0.015 0.15 / / / 0.11-0.16 0.020
L80 0.15-0.22 1.00 0.25-1.00 0.020 0.010 12.0-14.0 0.20 0.20 / / 0.020
J P110 0.26-035 0.17-0.37 0.40-0.70 0.020 0.010 0.80-1.10 0.20 0.20 0.15-0.25 0.08 0.020
Mechanical Properties of API 5CT
Steel Grade Yield Strength (Mpa) Tensile Strength (Mpa)
J55 379-552 ≥517
K55 ≥655 ≥517
N80 552-758 ≥689
L80 552-655 ≥655
P110 758-965 ≥862
API Spec 5CT standard replaced by:
  • 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
  • This product references:
  • API Spec 5B – Specification for Threading, Gauging, and Thread Inspection of Casing, Tubing, and Line Pipe Threads (US Customary Units) (Includes March 2004 Addendum)
  • ISO 10422:1993 – Petroleum and natural gas-industries; threading, gauging, and thread inspection of casing, tubing and line pipe threads; specification
  • This product replaces:
  • API 5CT – Specification for Casing and Tubing (U.S. Customary Units)
  • ISO 11960 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 5, Casing, tubing and drill pipe.


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