EN 10204 3.1 is the inspection certificate type export buyers most often name on a purchase order for stainless fittings and valves: a document in which the manufacturer declares the products meet the order and supplies test results from specific inspection, validated by an inspection representative independent of the production department. The standard defines the types — 2.1, 2.2, 3.1 and 3.2 — and knowing which one your order needs is the difference between clean customs and a customs hold. Here is the full map.
Key takeaways
- EN 10204 defines four inspection documents: 2.1 declares compliance without test results, 2.2 adds non-specific results, 3.1 adds specific results validated by the manufacturer’s inspection representative independent of production, and 3.2 adds the purchaser’s or an officially designated inspector’s countersignature.
- The results tie to the melt heat, not to each machined fitting: the heat number on the certificate and the marking on the parts are the traceability link, and both must be present.
- Name the certificate type, the standard to certify against, the grade and any third-party requirement on the RFQ — certificate scope is confirmed at quotation, not assumed.
What EN 10204 is
EN 10204 is the European standard for inspection documents on metallic products, now the global procurement language for steel certification. It superseded the older German DIN 50049, and its four current types replaced the old 3.1A/3.1B/3.1C alphabet — today’s 3.1 is the old 3.1B, and 3.2 absorbed the externally inspected variants. The paperwork travels with the same customs wave as the rest of the export file, alongside the HS codes and the shipping terms.
EN 10204 document types at a glance
| Type | Common name | Issued / validated by | What it attests | Typical use |
|---|---|---|---|---|
| 2.1 | Declaration of compliance | Manufacturer | The products comply with the order — no test results | Routine commercial orders where the buyer wants a statement, not data |
| 2.2 | Test report | Manufacturer | Compliance plus test results from non-specific inspection — results are not necessarily from the supplied batch | General industrial supply where typical values suffice |
| 3.1 | Inspection certificate | Manufacturer, validated by its authorized inspection representative independent of the manufacturing department | Compliance plus results of specific inspection — the products supplied or their defined test unit | The default for process-industry fittings, valves and pressure parts |
| 3.2 | Inspection certificate | The manufacturer’s independent representative and the purchaser’s representative, or an inspector designated by official regulations | The 3.1 content with independent validation added | Critical duty, owner or EPC specifications, regulated pressure equipment |
The row that matters for most buyers is 3.1: the validating representative’s independence is the definition — someone in the manufacturer’s organization, outside production, signs for the results. Type 3.2 keeps the same content and adds a second validating party, for when the purchaser or a regulation wants eyes from outside the mill.
The MTR, and the heat-number nuance
In US usage the same document goes by mill test report or mill cert, and an MTR reports what a 3.1 does: measured chemical and mechanical results tied to a standard and a purchase order. But the label is not the guarantee — an MTR counts as 3.1-equivalent only when it meets the order’s documentation requirements, independent validation among them. When a US drawing says “MTR” and a European spec says “3.1”, name the exact type on the RFQ rather than assume the words swap.
Here is the nuance most explainers skip, and it matters for machined parts. A 3.1 certificate’s results come from specific inspection of the defined test unit — for bar stock, the heat. The values describe the melt, not each individually machined fitting; the heat number marked on the parts ties your box of fittings back to that melt, and certificate and marking travel together or the paperwork proves nothing about the parts. Check marking against certificate at receiving, and name the grade the results certify against — 316 versus 316L is a certificate-level decision, as covered in 316 vs 316L.
3.1 vs 3.2 for export buyers
Type 3.1 is the de-facto default in plant, process and oil-and-gas procurement. Type 3.2 enters when the duty is critical, the owner or EPC specification demands external validation, or a regulation designates an inspector. The trade-offs are commercial: 3.2 adds third-party fees and an external schedule to the delivery path. Specify it because the duty demands it, not by habit.
What to write on the RFQ
Five lines turn certificate ambiguity into a clean quote, per the same checklist discipline as the RFQ writing guide:
- Certificate type by name — 2.2, 3.1 or 3.2. “MTR” alone is ambiguous across borders.
- Standard to certify against — for general stainless bar and shapes used to machine fittings, ASTM A276 is the usual citation; A479 is the pressure-vessel bar specification, named when the code calls for it. Forgings, tube and castings carry their own standards — name the product form’s standard.
- Material grade — SS304, SS316 or SS316L per line, so the certificate limits match the order.
- Third-party inspection — whether 3.2 validation is required, and by whom.
- Client or EPC template — if the project issues its own certificate format or content list, attach it so the paperwork matches the spec the first time.
How FerruleX handles certificates
An honest note — this page teaches the standard; it does not advertise inventory: certificate requirements are confirmed at quotation and named on the RFQ. Certificate type, standard certified against and third-party inspection are agreed before the order enters production — the paperwork is part of the product, and it is scoped like one. Sending “3.1 to ASTM A276, 316L, per attached template” with the size list gets documents that match your receiving inspection. Request a factory quote.
FAQ
Is an MTR the same as a 3.1 certificate? In practice they serve the same purpose — measured results tied to a heat — but they are not formally interchangeable. An MTR counts as 3.1-equivalent only if it meets the order’s requirements, including validation by an independent inspection representative. Name the EN 10204 type on the RFQ.
Is a 2.2 test report ever enough? Yes, where the duty accepts non-specific results: general industrial supply, non-pressure hardware, orders where typical values suffice. Process and pressure-part purchases commonly ask 3.1. The duty and the project spec decide, not habit.
What does a heat number tell me? It identifies the melt your material came from and links the certificate’s results to that melt — not to each individually machined part. The marking on the parts ties your fittings to the certificate; the two must match or the document does not describe your parts.
Does a 3.2 certificate cost more and take longer? Commonly yes: the purchaser’s representative or a designated inspector must validate the document, adding fees and an external schedule to the order. Specify 3.2 where the duty, owner specification or regulation requires external validation, and plan the time in.
Can certificates be issued after delivery, or for stock items? Often yes, if traceability survives — heat numbers recorded, inspection records retrievable. It is slower and riskier than naming the certificate on the order, so the RFQ line is the reliable path, not the afterthought.
Related: investment cast vs machined fittings.
