Typically, for ASME B&PV code applications, the carbon content is limited 0.35% for assignment of P-No's regarding weldable material. I don't believe there is a specific assignment of a P-No for this material.
To have a P number, the material has to be in an ASME material specification. AISI spec material does not have P numbers. There is often ASME material similar to the AISI than can be used, but don't have anything handy at the moment. There are also some select ASTM/API type materials that have S Numbers that are used in the B31 codes. Otherwise, the material has to be used as an unclassified material when it comes to welding P numbers.
