What is the difference between ASTM A335 P11 and P22
Jan 06, 2026
P11 and P22 are two different alloy steel pipe materials, mainly differing in chemical composition, high-temperature resistance, and application scenarios. P11 (corresponding to the national standard 15CrMoG) contains 1% chromium and 0.5% molybdenum, while P22 (corresponding to the national standard 12Cr2MoG) contains 2.25% chromium and 1% molybdenum. The latter has superior high-temperature strength and oxidation resistance, making it suitable for boiler systems with higher parameters.
Chemical Composition Differences
P11: Approximately 1% chromium and 0.5% molybdenum, belonging to low-alloy chromium-molybdenum steel.
P22: 2.25% chromium and 1% molybdenum, with higher alloying elements, significantly improving thermal strength.
Performance Comparison
Temperature Limit: P11's long-term operating temperature limit is approximately 550°C, while P22 can reach 580°C.
Oxidation Resistance: Due to its higher chromium content, P22 forms a more stable oxide film at high temperatures. Creep Strength: P22 exhibits approximately 30% higher creep strength at 580°C than P11.
Below is a video comparing the performance of P11 and P1+:
Application Scenarios
P11: Primarily used in superheaters, reheaters, and other components of medium- and high-pressure boilers (pressure ≤ 9.8 MPa).
P22: Suitable for main steam pipes and headers in supercritical units (pressure ≥ 9.8 MPa).
A335 P11 P22 boiler tube for sale
