A producer has questioned the basis for the coarse-grain melting practice requirement for P2 and P12 material in subsection 5.2. It is believed that this requirement has little to do with requiring a fine grain size in the finished product, but rather has been a means of preventing the use of aluminum for deoxidation, because of the long-held opinion that aluminum promoted graphitization in these alloys. Recent research indicates that aluminum is not a significant factor in promoting graphitization of these alloys. This action proposes to remove subsection 5.2 from the body of the specification and to add a supplementary requirement to limit use of aluminum for deoxidation of P2 and P12 pipe for those who may still want this restriction.
Keywordsalloy steel pipe; high temperature service; seamless steel pipe; steel pipe; temperature service applications: Alloy steel pipe--specifications; Ferritic steel pipe--specifications; High-temperature service applications--steel pipe; Hydrostatic testing; Seamless steel pipe--specifications;
Ballot Item Approved as A335/A335M-2015A and Pending Publication