API 2H — Tempered carbon manganese steel plates for offshore platforms (pipeline accessories)
Grades
Gr.42, Gr.50, Gr.55
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| Gr.42 | C≤0.21, Mn≤1.35, P≤0.040, S≤0.050, Nb+V 0.01-0.15 | Rm ≥415 MPa, Rp0.2 ≥290 MPa, A≥24% |
| Gr.50 | C≤0.23, Mn≤1.35, P≤0.040, S≤0.050, Nb+V 0.01-0.15 | Rm ≥450 MPa, Rp0.2 ≥345 MPa, A≥21% |
| Gr.55 | C≤0.25, Mn≤1.35, P≤0.040, S≤0.050, Nb+V 0.01-0.15 | Rm ≥485 MPa, Rp0.2 ≥380 MPa, A≥20% |
Application scope
API 2H specifies quenched and tempered (QT) carbon manganese steel plates for offshore platform structures, with three strength grades: Gr.42, Gr.50, and Gr.55. These are high-performance structural steels for marine engineering. The standard specifies requirements for composition, tensile strength, and low-temperature impact resistance. They possess high strength, excellent low-temperature toughness, and weldability, making them suitable for load-bearing structures such as jackets and pipeline supports on offshore platforms.
Typical applications
It is mainly used in offshore platform jackets, legs, joint pipes, and pipeline support structures that bear heavy loads and operate in low-temperature environments. Thanks to the high strength, excellent low-temperature toughness, and good weldability resulting from heat treatment, it meets the stringent safety and fatigue resistance requirements of marine engineering, making it suitable for critical load-bearing components such as jacket joints, legs, and pipeline ancillary structures.
