What is SA 335 P12 material
Jan 06, 2026
SA335 P12 is a chromium-molybdenum alloy steel pipe under the ASTM standard, with a chemical composition of 1Cr-0.5Mo (C<0.15%, Cr0.8-1.25%, Mo0.44-0.65%). Its high-temperature strength is significantly improved through the solid solution strengthening effect of aluminum. Compared to ordinary 20G boiler tubes, its creep strength at 540°C is increased by approximately 40%, and the allowable stress can reach 78MPa (ASME standard). This material must simultaneously meet the triple standards of ASTM A335 (materials), A213 (cold drawing), and A370 (mechanical testing), and must undergo 100% eddy current testing and hydraulic testing (test pressure >60MPa) before leaving the factory.
Specification
P12 steel pipes are typically available in sizes ranging from 25-762mm in diameter and 3-50mm in wall thickness.
Key Technologies in Production Process
The production of high-quality SA335 P12 steel pipes requires control over three core aspects:
1. The smelting process employs the EAFLFVD triple process, controlling sulfur and phosphorus content to ≤0.015% and hydrogen content to ≤2ppm;
2. Hot rolling utilizes a two-stage controlled rolling process, with the final rolling temperature controlled at 880±20℃ to ensure complete austenite recrystallization;
3. Heat treatment must adhere to a normalizing (900-930°C) and tempering (680-730°C) regime, resulting in a uniform tempered bainite microstructure.
Applications
In supercritical boiler units, P12 steel pipes are mainly used in:
Low-temperature superheaters (wall temperature ≤450°C)
Economizer headers
Main steam pipe support systems
SA335 P12 high temperature alloy pipe factory
