EN 10204 is acertificate typestandard — it specifies "what is written in this document and who signs it," not the material standard. So the phrase "require EN 10204 3.1" is incomplete on its own — you also need to specify the material grade and the governing standard (e.g., 316L / EN 10088-2).
One-Sentence Verdict
3.1 means the manufacturer inspects and signs on its own; 3.2 means manufacturer inspection + signature by an independent third party (inspection agency or user-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 Between Certificate Types
- 2.2: Declaration of conformity, 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'sauthorized inspector, providing measured chemical composition and mechanical properties for the batch, traceable to the heat number.
- 3.2: Builds on 3.1 — the inspection process is witnessed and signed by athird 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 someone witnessed the inspection," not "whether the data is accurate."Many projects treat the two as a "grade hierarchy," but the selection basis should really beconsequence 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 During Procurement
When you receive the certificate, don't just look for the words "3.1" — verify item by item:
- Heat number consistency: The heat number on the certificate must match the steel marking/label — 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 the solution/annealing condition clearly — 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 agency is oneaccepted by the user;
- Standard number: EN 10204 is a certificate standard; the material standard must also be stated (e.g., EN 10088-2 / ASTM A240).
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 thewitnessing entityis different, and the supervisor will not accept it;
- The third-party stamp is the trader's own inspection company, not an agency accepted by the user;
- The certificate is a photocopy/scan instead of the original, with no straddle seal and no verification method;
- Only the certificate is checked, not the physical steel stamp — if goods and certificate don't match, accountability becomes impossible.
We can provide EN 10204 3.1 material certificates with each batch (including measured chemical composition and mechanical properties, traceable heat numbers), and can also cooperate with your designated third party for 3.2 witnessing — to determine which one you need, first send us the project's material standard and acceptance clauses.
