ASTM A387/A387M — Chromium-molybdenum alloy steel plates for pressure vessels
Grades
Gr.2(0.5Cr-0.5Mo), Gr.12(1.25Cr-0.5Mo), Gr.11(1.25Cr-0.5Mo-Si), Gr.22(2.25Cr-1Mo), Gr.5(5Cr-0.5Mo), Gr.9(9Cr-1Mo), Gr.91(9Cr-1Mo-V-Nb), Gr.21(3Cr-1Mo), Gr.22L(2.25Cr-1Mo-V), Gr.911(9Cr-1Mo-V-Nb-W)
Chemical composition and mechanical properties
| Grade | Chemical composition | Mechanical properties |
|---|---|---|
| Gr.2 | C≤0.21, Mn 0.55-0.80, P≤0.025, S≤0.025, Si 0.15-0.40, Cr 0.50-0.80, Mo 0.45-0.60 | Rm 380-550 MPa, Rp0.2 ≥230 MPa, A≥18%, Normalizing + Tempering |
| Gr.12 | C≤0.17, Mn 0.40-0.65, P≤0.025, S≤0.025, Si 0.15-0.40, Cr 0.80-1.15, Mo 0.45-0.60 | Rm 415-585 MPa, Rp0.2 ≥275 MPa, A≥19%, Normalizing + Tempering |
| Gr.11 | C≤0.17, Mn 0.40-0.65, P≤0.025, S≤0.025, Si 0.50-0.80, Cr 1.00-1.50, Mo 0.45-0.65 | Rm 415-585 MPa, Rp0.2 ≥310 MPa, A≥19%, Normalizing + Tempering |
Application scope
ASTM A387/A387M specifies chromium-molybdenum alloy steel plates for high-temperature and high-pressure vessels, typically delivered normalized and tempered, and includes several chromium-molybdenum grades such as Gr.11, Gr.22, and Gr.91. The standard emphasizes high-temperature resistance and hydrogen resistance, and is applicable to the manufacture of welded high-temperature pressure vessels.
Typical applications
Widely used in the shells and heads of oil refining hydrogenation reactors, high-temperature heat exchangers, and petrochemical high-temperature vessels, as well as pressure-bearing components and pipes in power plant boiler drums, headers, and other equipment. Chromium-molybdenum alloying provides excellent high-temperature strength and resistance to hydrogen and creep, making it suitable for critical pressure vessels and components that operate under long-term high-temperature, high-pressure hydrogen-containing conditions.
