Materials between the worlds: material number to UNS and ASTM grade

The counterparts

The table lists the materials we supply to EN with their UNS counterpart and the ASTM grades of the standards we trade (ASME and ASTM profiles). The UNS number names the alloy – S31603 is the low-carbon molybdenum austenitic, whether it is called 1.4404 or 316L. It names nothing else: the product standard determines analysis bands, heat treatment and test scope, and those are not the same in EN 10222-5 and ASTM A182. The column “limits” says per material where the comparison ends.

Dual certified: one part, two standards

A product is dual certified when it meets the requirements of both worlds and the certificate names both standards – “1.4404 / 316L” or “A182 F316L / EN 10222-5 X2CrNiMo17-12-2”. This is possible where the analysis bands overlap and the test programme covers both standards. For austenitics it is state of the art: 304/304L and 316/316L almost always come from the mill with both numbers. For carbon steels it depends on the analysis (A106 Gr. B with P265GH, A105 with P250GH); for alloy, low-temperature and nickel steels heat treatment and impact testing differ so much that the mill issues one certificate per world.

Whoever needs dual certified material orders it so – “dual certified EN/ASTM, certificate 3.1 naming both standards”. There is no second certificate issued afterwards; what the mill has not tested it cannot certify.

3.1 certificate versus mill test report

The inspection certificate 3.1 to EN 10204 certifies that the delivery complies with the order – with analysis and mechanical values of the heat delivered, issued by a department of the mill independent of production. The mill test report (MTR, also certified material test report) certifies compliance with the ASTM standard – likewise with analysis and mechanical values, but to the test programme of the ASTM standard, which may know other test temperatures, specimen locations and tolerances. Both are mill certificates; they are not interchangeable because the reference standard is different. What a 3.1 contains is explained on Inspection documents to EN 10204.

Under the Pressure Equipment Directive. An ASTM material carries no presumption of conformity – it stands in no harmonised material standard. For pressure-retaining parts it needs a European Approval for Materials (EAM) or a particular material appraisal (PMA), in categories III and IV by a notified body. For parts outside the directive (below 0.5 bar, without pressure function) this does not apply. NACE MR0175 / ISO 15156 for sour service overlays both worlds: it prescribes hardness limits and material conditions that neither EN nor ASTM demand by themselves – whoever orders “NACE” orders in addition.

Further reading

The standards-worlds topic: Why standards are replaced · How binding standards are · Standards worlds by region · EN and ASME compared · Mixing standards worlds · Standards translator.

From our knowledge base: Standards guide · ASME and ASTM profiles · EN 1092-1 versus ASME B16.5 · ASME flange dimensions · Standards comparison · Inspection documents to EN 10204 · Reading markings · Identifying a component.