API 5L (海上级) — Seamless steel pipes for offshore pipelines
Grades
Gr.B, X42, X46, X52, X56, X60, X65, X70, X80 (PSL2, 海上级)
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| Gr.B | C≤0.17, Mn≤1.20, P≤0.035, S≤0.040 | Rm 345-450 MPa, Rp0.2 ≥185 MPa, A≥25% |
| X42 | C≤0.26, Mn≤1.40, P≤0.025, S≤0.015, Si (no requirements), Cr≤0.40, Cu≤0.40, Ni≤0.40, Mo≤0.15, V≤0.06, Nb+V≤0.06, Ti≤0.04, B≤0.001, N≤0.012 | Rm ≥415 MPa, Rp0.2 ≥290 MPa, A≥21% (gauge length 50mm), PSL2 has impact requirements. |
| X46 | C≤0.26, Mn≤1.40, P≤0.025, S≤0.015, Si (no requirements), Cr≤0.40, Cu≤0.40, Ni≤0.40, Mo≤0.15, V≤0.06, Nb+V≤0.06, Ti≤0.04, B≤0.001, N≤0.012 | Rm ≥435 MPa, Rp0.2 ≥317 MPa, A≥20% (gauge length 50mm), PSL2 has impact requirements. |
Application scope
API 5L Marine Class Specification for seamless pipeline steel pipes for offshore oil and gas transportation, using PSL2 delivery level, with grades including Gr.B and X42 to X80. The standard sets strict requirements for composition, tensile and impact toughness, emphasizing good weldability and crack arrest performance, and is suitable for oil and gas transportation pipelines with high pressure and corrosion resistance requirements, such as subsea and platform process pipelines.
Typical applications
Widely used in pressure-bearing components such as subsea pipelines, risers, platform process pipelines, and gathering and transportation pipelines in offshore oil and gas fields. Grades are classified by strength, allowing selection based on transmission pressure, medium, and marine environment. With its stringent PSL2 performance and crack arrest requirements, as well as excellent weldability, it is suitable for subsea and offshore oil and gas transmission systems subjected to long-term high pressure, corrosion, and external loads.
