Mill Test Certificate (MTC): What EN 10204 3.1 vs 3.2 Means and How to Read It

Every piece of certified metal you buy should arrive with a Mill Test Certificate (MTC) — also called a Material Test Report (MTR) or Certificate of Compliance. For buyers, the MTC is the single document that proves the material you received is the material you paid for. Yet most enquiry forms still just write "with certificate" without specifying which type, and that ambiguity is where costly disputes begin.

This guide explains the EN 10204 certificate types (2.1, 2.2, 3.1, 3.2), what each one actually guarantees, how to read the key fields, and what to require so your incoming inspection and your customer's audit both pass first time.

EN 10204 Certificate Types at a Glance

The practical difference: a 3.1 cert shows the real chemistry and mechanicals measured on your heat. A 2.2 shows typical values from some heat. For pressure equipment, structural, and code work, 3.1 is the minimum; 3.2 when a notified body or end-client requires independent witness.

How to Read a 3.1 Certificate (Field by Field)

Traceability rule: if the heat number on the bar, sheet or flange does not match the heat number on the MTC, the certificate is invalid for that piece — reject and request correction before use.

Common MTC Mistakes That Cause Rejection

1. "Certificate" unspecified — supplier ships a 2.2 when your project needs 3.1. Always write "EN 10204 3.1" in the PO.
2. Heat number mismatch — bundled stock mixed at the warehouse; require heat number stamped and matching.
3. Wrong standard cited — ASTM order with an EN-only certificate (or vice versa); ask for the certificate in the same standard family.
4. No IGC / UT where needed — chloride or code service needs ASTM A262 E and/or UT per A388; list them explicitly.
5. 3.1 instead of 3.2 for offshore/code — DNV/Lloyd's/ASME U-stamp jobs often demand the third-party 3.2.

When You Actually Need 3.2

• Pressure Equipment Directive (PED) / ASME U-stamp vessels
• Offshore and sour service (NACE MR0175 / ISO 15156)
• Nuclear, aerospace, and medical critical parts
• Any contract where the end-client's QA requires an independent witnessed certificate

For standard commercial orders, 3.1 is sufficient and faster — reserve 3.2 for where code or contract demands it, since it adds inspector cost and lead time.

How to Specify the Certificate in Your Enquiry

Add one clear line to every purchase order:

"Material to be supplied with EN 10204 3.1 Mill Test Certificate, heat-number traceable, including chemistry, mechanicals, [UT per A388, IGC per ASTM A262 E as applicable]. 3.2 third-party inspection by [TUV/BV/SGS] where required by project."

Frequently Asked Questions

Is a 3.1 certificate the same as a CoC? A Certificate of Compliance (CoC) is often a 2.1 declaration. A 3.1 is a tested certificate with real values. Never assume "CoC" equals "3.1" — state the type.

Can the supplier back-date or change an MTC? No — a legitimate 3.1 is generated against the recorded heat test data at the mill. If values are altered, the heat number traceability breaks and the document is fraudulent. Buy only from suppliers who provide mill-origin certificates.

Do you provide MTC in English? Yes — our 3.1/3.2 certificates are issued in English with full test values and heat traceability, and we can pre-send a certificate sample for your QA review before dispatch.

What if a third-party 3.2 is needed urgently? 3.2 requires inspector scheduling at the mill; build 1–2 weeks into the plan. For routine stock items, 3.1 ships immediately.

Request Certified Material with Full MTC

Shanghai Hangbo Alloy Group ships every order with EN 10204 3.1 Mill Test Certificates as standard, heat-number traceable to the material, and 3.2 third-party certification (TUV / BV / SGS / DNV / Lloyd's) on request. Tell us your standard, grade and required tests — we include a certificate sample with every quote for your QA review before you commit.