EN 10204 material certificates: what a 2.2, a 3.1 and a 3.2 say

October 21, 2026  ·  Indumor

A material certificate is like a blood test for a steel plate: it says where it comes from, what it has inside and how it responded to testing. And, as with a blood test, keeping it in the binder is not enough: you have to know how to read it and, above all, whether it belongs to the right patient.

The standard that organizes these documents is EN 10204, which sorts them into four types. In practice, the discussion almost always comes down to two: the 2.2 and the 3.1.

The four types, one line each

• 2.1, declaration of compliance: the manufacturer declares that the product meets the order. No test results.
• 2.2, test report: it has results, but from non-specific inspection: from production in general, not necessarily from what you received.
• 3.1, inspection certificate: it has the results of tests performed on the product delivered, validated by the manufacturer's authorized inspection representative, independent of the manufacturing department.
• 3.2, inspection certificate with two signatures: besides the manufacturer's inspector, it is validated by the purchaser's representative or an inspector designated by official regulations.

Asking a 2.1 for test results is like trying to get blood out of a stone: it does not have them.

2.2 or 3.1

The 2.2 tells you how that product generally comes out of that mill. It works for jobs where the material is not critical and the specification asks for nothing more: a warehouse guardrail, a light structure with no particular requirements. It is easy to get and adds no cost.

The 3.1 tells you exactly how the steel in your shop came out. It carries the heat number, which has to match the one marked on the plate or section, and with it traceability is built: which heat each piece of the structure came from. It is what mining, oil and gas, pressure vessels and any serious specification ask for.

The verdict: if the project says nothing and the material is not critical, a 2.2 is enough. If the project calls for traceability, if the part works under pressure, fatigue or cold, or if there is a quality dossier involved, it is a 3.1; and a 3.2 when the client or the code wants its own inspector.

What to check on a 3.1

• The heat number, and that it matches the marking on the material.
• The standard and grade ordered: ASTM A36 is not A572 Grade 50.
• The chemical composition, with the carbon equivalent if weldability matters: CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15.
• Mechanical properties: yield strength, tensile strength and elongation, within what the material standard requires.
• Charpy impact test, with its temperature, if the project calls for it.
• The certificate type declared and the signature of whoever validates it.

The most common mistakes

• The certificate is for a different heat. The paper is there, the grade is right, but the number does not match the plate. It is worth the same as having nothing.
• A photocopy of a photocopy, where the values can no longer be read. Ask for the original or a legible file.
• The distributor's document instead of the mill's. If the material goes through a distributor, the right thing is for them to pass on the manufacturer's original certificate, unchanged, not a document of their own that replaces it.
• Similar grades that are not the same. A European S355 and an ASTM A572 Grade 50 are cousins, not twins: their minimum values and tests do not fully match. If the drawing names one, it does not get swapped for the other without the engineer's approval.

For stainless and alloy steels, some specifications also call for positive material identification: a test with a handheld analyzer that confirms, in the shop, that the plate is the grade the paper says. It is quick, and it prevents the most expensive mix-up of all, a 304 that turned out to be something else.

A detail that gets forgotten: when a plate is cut, the heat number has to be transferred to every piece. Otherwise the certificate is still valid, but nobody knows which piece it refers to anymore. In the United States this document is usually called a mill test report (MTR); the content is the same. And it is kept with the dossier for the whole life of the structure: if it has to be repaired or extended twenty years from now, it is the paper that says what steel is there.

If your project calls for 3.1 certificates and traceability, tell us when you request a quote: we include them in the quality dossier from the first cut. And if you are not sure which certificate applies, send us the specification at Indumor and we will tell you at no charge. If you are putting the order together, see also how to request a quote you can compare.

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