ASTM A335 Grade P91 is a specification for seamless alloy steel pipes intended for high-temperature service. Here's a detailed overview:
ASTM A335 Grade P91 Alloy Steel Pipe
1. Material Type:
Alloy steel, specifically a chromium-molybdenum (Cr-Mo) steel.
2. Composition:
Primarily designed with about 9% Chromium (Cr) and 1% Molybdenum (Mo).
Other elements typically include Carbon (C), Manganese (Mn), Silicon (Si), Nickel (Ni), and Vanadium (V), optimized for high strength and resistance to high-temperature creep.
3. Applications:
Used in power plants, refineries, and petrochemical industries.
Suitable for high-temperature and high-pressure services such as steam pipelines, heat exchangers, boilers, and superheaters.
Excellent resistance to oxidation and creep at elevated temperatures.
4. Key Properties:
High-temperature strength: Maintains strength at temperatures up to about 600–650°C (1112–1202°F).
Creep resistance: Designed for long-term exposure to elevated temperature and stress.
Good weldability: Can be welded using proper procedures; post-weld heat treatment (PWHT) is generally required.
Corrosion resistance: Good resistance to oxidation in high-temperature environments.
5. Specification Details:
ASTM standard: ASTM A335/A335M
Grade: P91
Type: Seamless pipe
Size range: Typically from 1/2' to 48' diameter (varies by manufacturer)
Wall thickness: Various, depending on schedule
