A351 CF8M vs SA351 CF8M
iainuts (Mechanical) 8 May 06 19:21. Material per ASTM specifications are preceeded by the A, hence the A351. ASME code materials for pressure vessels take this ASTM spec, and then add test requirements to them. The ASME Code material for vessels then gets an S before the ASTM spec, hence the SA351 designation.