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ASTM A335 P91 is a high-strength chromium-molybdenum-vanadium alloy steel seamless pipe designed for high-temperature and high-pressure service. It is produced under the ASTM A335 / ASME SA335 specification, which covers seamless ferritic alloy steel pipes commonly used in power plants, refineries, petrochemical facilities, and industrial heating systems.
Grade P91 is a 9Cr-1Mo-V-Nb alloy steel known for its exceptional creep strength, oxidation resistance, and long-term stability at elevated temperatures. The alloy composition typically includes 8β9.5% chromium and around 0.85β1.05% molybdenum, along with vanadium, niobium, and nitrogen, which improve high-temperature strength and resistance to deformation under stress.
