mill test certificate · EN 10204 · 3.1 · 3.2 · inspection
How to check a mill test certificate: 3.1 vs 3.2
EN 10204 3.1 certificates are issued by the manufacturer's inspection department; 3.2 by an independent inspection body. Verify heat numbers, chemistry, mechanicals, standard and signatures.
The mill test certificate (MTC) is the core document at acceptance of stainless steel. Two common EN 10204 types:
• 3.1 certificate: issued by the manufacturer's inspection department, declaring conformity to the order and including measured chemical composition and mechanical properties.
• 3.2 certificate: issued by an inspection body independent of the manufacturer, typically required for pressure, safety or customer-mandated applications.
What to check:
1) Heat/coil number matches the physical label and packaging.
2) Grade and standard match the order (e.g. 316L per ASTM A240 / 1.4404 per EN 10088-2).
3) Measured chemistry is within the standard range, especially Cr/Ni/Mo/C.
4) Mechanical properties (yield, tensile, elongation) meet the standard and any additional customer requirements.
5) Heat treatment/delivery condition and surface code are correct.
6) Signatures, authorised person, date and certificate number are present; a 3.2 certificate must identify the independent body.
Good practice: request traceable heat numbers and third-party retest reports; for critical parts, carry out your own PMI (spectrometer) verification.
Remember: a certificate is a declaration, not proof that the physical goods conform — incoming inspection and PMI remain necessary.
