What is the difference between P9 and P91 steel pipe?

P9 pipes of the ASTM A335 grade are produced with higher alloying elements compared to general carbon pipes. The ASTM A335 P9 Pipe is composed of chemical composition of 8-10% chromium, 0.25-1% silicon and 0.90-1.10% molybdenum. It also has small amounts of carbon, manganese, phosphorous, and sulfur. 

P91 is a chrome moly alloy metal that contains excellent strength and temperature resistance. It is designed for enhanced creep strength, making it a creep strength enhanced ferritic (CSEF). This metal is made by normalizing at 1050 °C, air cooling to 200 °C, and then tempered through heating to 760 °C.

P91 is a modified form of P9 (9 percent chromium, 1 percent molybdenum) steel. The steel can have low impurity limits, thanks to the development of processes such as argon-oxygen decarburization (AOD) and electroslag remelting (ESR), which make the steel behave consistently during fabrication and resist the effects of aging. When properly heat-treated as specified in ASTM specification A335, the steel acquires room temperature properties.

BBN steel can supply P9 and P91 steel. If you have these demands, please contact us freely.

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