API 2H — Tempered carbon manganese steel plates for offshore platforms
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 carbon manganese steel plates for offshore platform structures. It belongs to the API standard system and includes grades Gr.42, Gr.50, and Gr.55. The standard achieves a good balance of strength and toughness through quenching and tempering, specifies composition, tensile strength, and low-temperature impact requirements, emphasizes excellent low-temperature toughness and weldability, and is approved by the relevant system. It is suitable for welded structures of joints and load-bearing components on offshore platforms.
Typical applications
Primarily used in critical load-bearing components of offshore oil platforms such as jackets, legs, deck structures, and joint pipes, especially suitable for pipe joint areas with stress concentration. Grades are classified by strength, allowing selection based on stress and plate thickness. Thanks to the excellent strength-toughness combination, low-temperature toughness, and weldability resulting from tempering, it is suitable for stationary platform structures subjected to long-term cyclic loads and low-temperature marine environments.
