Difference between ASTM A and ASME SA

The difference between an A and SA designation has to do with the ASME Boiler and Pressure Vessel Code approval of a material. If a material is supplied to an SA material specification, it meets the requirements of the ASME Boiler and Pressure Vessel Code, Section II, and can be used in items manufactured according to the code.

The ASME code accepts the ASTM materials with some additional specified properties. So if your equipment is manufactured to the ASME Boiler Pressure vessel code, the list below applies.

Example: Stainless steel pipe 312 TP 304 according to ASME compliance..

ASME SA312 TP304
ASME: Applicable Standard
S: ASME approved Material
A: Ferrous
312: Manufacturing Process No.
TP: Tubular Product
304: Grade

In ASME material, it is SA312 and not simply A312. So when the prefix S is added to the material type, it indicates ASME approved material, and that's the difference.

ASME has adopted ASTM material with additional requirements; therefore, this numbering differs slightly.

For some material grades, there is no difference between ASTM and ASME. However, for some, there are certain additional requirements. To comply with the ASME boiler pressure vessel code, you must take these differences into account during material inspection.

Many manufacturers produce their material with dual marking on the material so that it can be used for both ASME and ASTM.