ASTM A335 Alloy Boiler Steel Pipe Standard specification for seamless ferritic alloy-steel pipe for high-temperature service. ASTM A335 Pipe (ASME S/A335, Chorme-Moly) is a seamless ferritic Alloy-Steel Pipe for high temperature service. Pipe ordered to this specification shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Sometimes referred to as “P Grade”, Chrome Moly Pipe is popular in P-Grades P5, P9, P11, P22, and P91. The most common use of grades P11, P22, and P91 is in the power industry and petro-chemical plants, Grades P5 and P9 are commonly used in refineries. A335 is often called chrome moly pipe because of the chemical makeup of Molybdenum (Mo) and Chromium (Cr). Molybdenum increases the strength of steel as well as the elastic limit, resistance to wear, impact qualities, and hardenability. Moly increases the resistance to softening, restrains grain growth and makes chromium steel less suscep…