EN 10204 is a certificate type standard: it specifies "what is written in this document and who signs it," not the material standard. So the phrase "we need EN 10204 3.1" is incomplete on its own — you also need to state the material grade and the governing standard (e.g. 316L / EN 10088-2).
One-sentence verdict
3.1 means the manufacturer inspects and signs for itself; 3.2 means manufacturer inspection + signature by an independent third party (an inspection body or the user's designated representative). When a project or end customer requires 3.2, substituting 3.1 is non-compliant; conversely, for general applications 3.1 is sufficient, and the extra third-party witness fee is unnecessary.
Practical differences among certificate types
- 2.2: Declaration of compliance, without specific inspection results (no measured chemical composition or mechanical values). Generally used only for non-pressure, non-critical parts.
- 3.1: Signed by the manufacturer's authorized inspector, supplied with the batch's measured chemical composition and mechanical properties, and traceable to the heat number.
- 3.2: On the basis of 3.1, the inspection process is witnessed and signed by a third party independent of the manufacturer (the third party may be an inspection company commissioned by the user, or the user's own resident representative).
In other words: the difference between 3.1 and 3.2 is "whether the inspection was witnessed," not "whether the data is accurate." Many projects treat the two as "higher vs. lower grade," but the basis for selection should really be consequence of failure: pressure-bearing, flammable/explosive, and safety-critical parts require 3.2; general structural and decorative parts are fine with 3.1.
What to check in procurement
When you receive a certificate, don't just look at the words "3.1" — check item by item:
- Heat number consistency: The heat number on the certificate must match the marking/label on the steel — this is the most common point of fraud (the certificate is genuine, but the goods are not from that heat);
- Measured chemical composition: Not the standard range, but the measured values, and they must fall within the range; focus on C (316L requires ≤ 0.03%), Ni, Cr, Mo;
- Mechanical properties: Yield, tensile, elongation; if impact requirements apply, also check the test temperature;
- Heat treatment condition: For stainless steel, state clearly the solution-annealed/annealed condition — the same grade in different conditions can differ greatly in corrosion resistance;
- Signing entity: For 3.1, check whether it is the manufacturer's authorized inspector; for 3.2, check whether the third-party body is the one approved by the user;
- Standard number: EN 10204 is the certificate standard; the material standard (e.g. EN 10088-2 / ASTM A240) must also be stated.
Common pitfalls
- The project requires 3.2, but the supplier provides 3.1 and says "the content is the same" — the content may be the same, but the witnessing entity is different, and the supervisor will not accept it;
- The third-party stamp is the trader's own inspection company, not a body approved by the user;
- Photocopies/scans are used instead of originals, with no page-seam stamp and no verification method;
- Only the certificate is checked, not the physical steel stamp — if goods and certificate don't match, there is no way to hold anyone accountable.
We can supply EN 10204 3.1 material certificates with each batch (including measured chemical composition and mechanical values, traceable heat number), and can also cooperate with your designated third party for 3.2 witnessing — to decide which one you need, send us the project's material standard and acceptance clauses first.
