A 3.1 certificate shows heat number, grade, standard, diameter, chemistry, tensile strength, elongation and any special tests such as torsion, wrap, coil test or intergranular corrosion. Spring wire adds coiling test results; medical wire adds inclusion rating and traceability.
Check the heat number on the coil tag against the certificate, and check that the chemistry meets the L grade limits if welding is planned. For welding wire, the certificate should follow the filler standard (EN ISO 14343 or AWS A5.9) rather than the base metal standard.
3.2 certificates, validated by an independent inspector, are required for some pressure, nuclear and aerospace work.