Almost every technical specification for pressure equipment, piping and structural steel asks for a material certificate — and most say it in one line: "EN 10204 3.1 required". Getting the type wrong on an RFQ either forces a re-quote later or, worse, delivers equipment with paperwork the end client will reject at receiving inspection.
What EN 10204 actually is
EN 10204 is a European standard, Metallic products — Types of inspection documents, that defines four types of document a manufacturer can issue to certify that a delivered product complies with the order. It does not set the technical requirements themselves (those come from the material or product standard, e.g. ASTM A105 or ASTM A234) — it standardises how compliance is documented and who is allowed to validate it.
The four certificate types
| Type | What it certifies | Validated by |
|---|---|---|
| 2.1 | A declaration of compliance with the order — no test results included | The manufacturer |
| 2.2 | A test report with results from non-specific testing — i.e. not necessarily from the same batch as the delivered product | The manufacturer |
| 3.1 | An inspection certificate with results from specific testing, traceable to the actual product delivered | A person independent of the manufacturing department (the manufacturer's own inspection/QA function) |
| 3.2 | An inspection certificate with results from specific testing, traceable to the actual product delivered | The manufacturer's authorized inspection representative independent of manufacturing, together with the purchaser's authorized inspection representative or the inspector designated by official regulations |
The practical line to remember: 2.1 and 2.2 are the manufacturer simply saying so; 3.1 and 3.2 are traceable, specific test results tied to the actual delivered item, with 3.2 adding an independent second signature.
3.1 vs 3.2 — the distinction that matters most
For pressure-containing parts in oil and gas — flanges, fittings, pipe, pumps casings, bolting — EN 10204 Type 3.1is the default requirement on most specifications: it gives full traceability of chemical and mechanical test results to the specific heat/batch, validated by the manufacturer's own quality department acting independently of production. Type 3.2is reserved for higher-criticality items where the project, an applicable pressure equipment directive, or the end client's specification requires an additional, genuinely independent validation — either a third-party inspector or the purchaser's own authorised representative — witnessing or reviewing the same test results.
How to specify it correctly
When writing a line item, state the certificate type explicitly next to the material standard — for example "ASTM A105, EN 10204 Type 3.1" — rather than a generic note elsewhere in the document. If Type 3.2 is required, also state who the independent validating party should be (a named TPI agency, or the purchaser's representative), since that decision affects lead time and cost. For more on structuring the wider inspection scope around the certificate, see our guide to third-party inspection. Listing the right certificate type on every line item also belongs in the wider bill of quantities you send to suppliers.
Not sure which certificate type your project needs? Send us your specification and we can clarify the document requirement with you before seeking quotations.
Frequently asked questions
Is a 3.2 certificate always better than a 3.1?
It is more rigorous, not simply better — a 3.2 adds cost and lead time because it requires a second, independent validating party. Specify 3.2 only where the project or code genuinely requires it (for example certain pressure equipment directives or client specifications), not as a default for every item.
Can a supplier's own quality department issue a 3.1 certificate?
Yes, when it is the manufacturer's authorized quality or inspection representative and independent of manufacturing. The defining feature of a 3.1 certificate is that it is validated by a representative independent of the manufacturing department — typically the manufacturer's own inspection or quality assurance department, which must be organisationally independent from production, not simply a different signature from the same team.
Is EN 10204 the same thing as a mill test certificate (MTC)?
"Mill test certificate" is the common industry term for the document; EN 10204 is the European standard that defines the four official types of inspection document (2.1, 2.2, 3.1, 3.2) that an MTC can be issued as. When someone asks for "an MTC", always confirm which EN 10204 type they actually need.
Does EN 10204 apply outside Europe?
Yes — despite being a European (CEN) standard, EN 10204 certificate types are referenced globally in oil and gas procurement specifications, including in the Middle East, Asia and the Americas, because it is the most widely recognised classification for metallic product inspection documents.
