What Is The API Standard for Seamless Casing Pipe?

The API standard for seamless casing pipe is mainly API Spec 5CT. Its main contents are as follows:

Range of application

It specifies the technical delivery conditions for steel pipes (casing pipe, tubing and pup joints), coupling materials and accessory materials, and establishes requirements for three product specification levels (PSL-1, PSL-2, PSL-3). It is applicable to seamless casing pipe with short round threaded casing pipe (STC), long round threaded casing pipe (LC), partial trapezoidal threaded casing pipe (BC), special clearance casing pipe (XC), flat tubing (NU), thickened tubing (EU), integral joint tubing (IJ) and other connection forms according to API Spec 5B.

Dimension requirements

1. Outer diameter: usually ranges from 6.0mm-219.0mm.

2. Wall thickness: 1.0mm-30mm.

3. Length: maximum length 12000mm.

Steel grade and chemical composition

1. J55

C content 0.34-0.39, Si content 0.20-0.35, Mn content 1.25-1.50, P≤0.020, S≤0.015, Cr≤0.15, Ni≤0.20, Cu≤0.20, Als≤0.020.

2. K55

C content 0.34-0.39, Si content 0.20-0.35, Mn content 1.25-1.50, P≤0.020, S≤0.015, Cr≤0.15, Ni≤0.20, Cu≤0.20, Als≤0.020.

3. N80

C content 0.34-0.38, Si content 0.20-0.35, Mn content 1.45-1.70, P≤0.020, S≤0.015, Cr≤0.15, V content 0.11-0.16, Als≤0.020.

4. L80

C content 0.15-0.22, Si≤1.00, Mn content 0.25-1.00, P≤0.020, S≤0.010, Cr content 12.0-14.0, Ni≤0.20, Cu≤0.20, Als≤0.020.

5. P110

C content 0.26-0.35, Si content 0.17-0.37, Mn content 0.40-0.70, P≤0.020, S≤0.010, Cr content 0.80-1.10, Ni≤0.20, Cu≤0.20, Mo content 0.15-0.25, V content 0.08, Als≤0.020.

Mechanical properties

1. J55: yield strength 379-552MPa, tensile strength ≥517MPa.

2. K55: yield strength ≥655MPa, tensile strength ≥517MPa.

3. N80: yield strength 552-758MPa, tensile strength ≥689MPa.

4. L80: yield strength 552-655MPa, tensile strength ≥655MPa.

5. P110: yield strength 758-965MPa, tensile strength ≥862Mpa.

Surface requirements

1. Surface roughness: it should meet international standards and be kept within a specific range to ensure its sealing and lubrication properties.

2. Surface cleanliness: the surface should be clean and free of impurities, and there should be no obvious oxide scale, rust and stains.

3. Surface coating: if it is necessary to apply a coating or coating on the surface of the steel pipe casing pipe, it should meet the relevant standards and ensure the adhesion and durability of the coating.

4. Surface hardness: the hardness of the surface should meet customer needs and be able to resist corrosion and wear in the external environment.

Summary

In short, the API standard guarantees the quality and safety of seamless casing pipe and promotes industry collaboration. Only by following it can casing pipe help various industries and promote industrial development.