Low Alloy Steel materials are produced in different specifications. The A335 is a specification for seamless ferritic alloy steel pipe. These Alloy steel seamless pipes are intended for high temperature services. There are also the High Alloy Steel materials. There are different grades in this material specification. There are P1, P2 through P91 and P92 grades. The most commonly used are the p5, p9, p11, p22, p91 and the p91 grades.