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Tubing and Casing, Line Pipes

J55 and K55 Oil Casing in API 5CT

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.
1. Heat treatment
PSL1 requirements: J55 and K55 same way (can be rolled-state delivery); PSL2 requirements: J55, K55 product should be normalized or normalized and tempered overall, if thick, should be normalized or normalized and tempered after thickened.

2. Tensile test
J55: yield strength of 379MPa ~ 552MPa; tensile ≥517MPa; minimum elongation of J55 is 19%.
K55: yield strength of 379MPa ~ 552MPa; tensile ≥655MPa; minimum elongation of K55 is 15%.

3. Impact test
J55 and K55 impact test must be done, the minimum size of the sample lateral impact energy 20J, the smallest full-size sample longitudinal impact energy 27J.

4. Wall thickness detection
PSL1: J55 and K55 for measuring the wall thickness of no coverage requirements;
PSL2: J55 and K55 for wall thickness measurement and recording deal with the entire length of the best coverage of the surface area of ​​automatic detection system should reach 25%.

5. NDT
PSL1: J55 and K55 on the tube did not do destructive testing mandatory requirements;
PSL2: J55 and K55 for all pipe shall be one or more of the criteria specified in 10.15.5 tested to find the inner surface of the outer surface of the pipe and can receive the level of L4 longitudinal imperfections.

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


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).

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