EN 10204 3.1 vs 3.2 Mill Test Certificates: Buyer Guide

Why the MTC Matters More Than the Quote

Two suppliers can offer the same A234 WPB elbow at the same price. One supplies it with a vague "test report" stamped by the workshop foreman. The other supplies it with a properly issued EN 10204 type 3.1 certificate cross-referenced to a specific heat number on the part.

When the elbow fails in service, the second supplier has a defensible paper trail. The first does not — and the buyer carries the liability. The MTC is your insurance policy, and EN 10204 is the international rulebook for what a valid MTC looks like.

The Four EN 10204 Certificate Types

Type 2.1 — when to use

Decorative or non-critical components only. Never accept for pressure-bearing parts.

Type 2.2 — never accept for fittings or flanges

Type 2.2 explicitly allows the test data to come from a different heat than the one you received. Heat traceability is broken. Useless for any safety-critical part.

Type 3.1 — the default for B2B fittings

This is what 90 % of EPC procurement specifications call for. Two non-negotiable requirements:

1. The QA representative who signs must be organizationally independent of the manufacturing department
2. The test data must be from the actual heat that the marked component was made from

Type 3.2 — when 3.1 is not enough

When you need a third party (typically the buyer's own inspector or an independent body like SGS, BV, Lloyd's, TÜV, or DNV) to witness the tests, the certificate is countersigned and becomes type 3.2.

What a Compliant 3.1 Must Contain (Buyer Checklist)

Before paying for the lot, verify the certificate has every one of:

• [ ] Heat / lot / batch number — must be traceable to the physical fitting marking (cross-check the hard stamp on the part)
• [ ] Chemical composition — full element list: C, Mn, P, S, Si, Cr, Mo, Ni, Cu, V, Nb, Ti + Carbon Equivalent (CEV)
• [ ] Mechanical properties — tensile strength (Rm), yield strength (Rp0.2), elongation %, hardness (HRB / HBW / HV)
• [ ] Charpy V-notch impact values if low-temperature service applies (test temperature, 3 specimen energies, lateral expansion)
• [ ] NDT results referenced in the body (UT / RT report numbers)
• [ ] Heat treatment record (normalising / quench-temper / solution annealing details)
• [ ] Signature + stamp of authorised QA representative (with name and title) + date
• [ ] EN 10204 type designation explicitly written (e.g. "EN 10204:2004 type 3.1")

Pipe Fittings Special Rule: the "Mother Material" MTC

For elbows, tees, reducers, caps and other processed products, the manufacturer must supply MTCs for:

1. The finished fitting itself
2. The mother pipe / plate used to fabricate it

The two certificates are linked by heat number. The fitting MTC must reference the mother-material MTC's heat number.

How to cross-check on the inspection floor:

• Fitting body hard-stamp shows heat number "ABC123"
• Finished-fitting MTC heat number = ABC123 ✓
• Finished-fitting MTC references "made from heat ABC123 of mother material to ASTM A106 Gr B"
• Mother-pipe MTC for heat ABC123 attached separately ✓

If the mother-material MTC is missing, the chain is broken — reject the lot.

When 3.1 Is Enough vs When You Must Specify 3.2

Red Flags When Reviewing a Chinese Supplier's MTC

1. Heat number on certificate doesn't match the fitting hard-stamp — fundamental traceability break
2. Type "3.1" issued under the logo of an inspection body (3.1 is by the manufacturer, not a third party — wrong format; if a third party is involved, the cert should be 3.2)
3. Missing CEV value on a low-temperature carbon steel grade
4. Sour-service order missing SSC / HIC results per NACE MR0175 / TM0284
5. Photocopy / scan only — no controlled original with embossed stamp; for critical orders demand the original or a watermarked digital with verifiable signature
6. Signature is the production manager's — that violates the "organizationally independent" requirement
7. NDT report references a date AFTER the certificate issue date — impossible

How to Write the MTC Requirement Into Your PO

Sample clauses you can copy:

Clause A — General
"All fittings and flanges shall be supplied with EN 10204:2004 type 3.1 mill test certificates as a minimum. Certificates shall be heat-number-specific, traceable to the physical hard-stamp on the part body, and signed by the manufacturer's QA representative who shall be organizationally independent of the manufacturing department."

Clause B — Critical service (sour / cryogenic / PED IV)
"Items marked with [code: SS / CR / PED-IV] in the BOM shall be supplied with EN 10204:2004 type 3.2 mill test certificates countersigned by [SGS / BV / TÜV / DNV] following witness of all required mechanical, chemical, and NDT testing per the project specification."

Clause C — Mother material
"For all processed fittings (elbows, tees, reducers, caps), the supplier shall provide both the finished-fitting MTC and the mother-material MTC, cross-referenced by heat number. Failure to provide both shall be grounds for rejection."

This article is provided as a procurement reference. Project specifications must follow the latest EN 10204 edition (currently 2004) and any project-specific overrides.

Related Products

For physical supply of the specs discussed above, refer to the relevant Hebei Haihao product categories:

• seamless butt-welding pipe fittings
• forged flanges and nonstandard forgings

Or browse the full product catalogue and filter by ASTM / ASME / EN / GB standards, material grades, and size ranges.

Further Reading

• ASME B16.9 pre-shipment inspection checklist
• NACE MR0175 sour service requirements

Next Steps

• This article is a procurement reference; all standard numbers, chemistry limits, and process parameters defer to the latest published edition
• For project RFQs, submit your specs via the inquiry form; we respond within 4 business hours
• Factory certifications and inspection capability are listed on the certificates page