A reading order for an EN 10204 3.1 certificate: heat number, chemistry, mechanicals, dimensions — and the two properties that decide whether the sheet forms cleanly.
Check four things on an EN 10204 3.1 certificate: the heat number matches the bundle marking, the chemical composition sits inside the alloy window, the mechanical properties (Rp0.2, Rm, A50) meet the temper, and the dimensions and quantity match the packing list. The certificate is only worth the paper if the heat number traces to the pallet you receive — the rest is a chemistry exercise you can do with the table below.
A mill certificate is a statement by the producer that a specific heat of metal met a specification. Inspection certificate 3.1 under EN 10204 is issued by the manufacturer's independent inspection representative and is traceable to the heat. That traceability is the whole point: without the heat number appearing on the bundle, the certificate describes metal that may not be in your container.
The layout differs between mills but the content does not. Below is the reading order we use when a customer sends a certificate and asks whether the sheet is what they ordered.
| Field | What it should say | How to check it |
|---|---|---|
| Standard and grade | EN 485-2 / ASTM B209, alloy and temper | Must match your purchase order, not just the alloy family |
| Heat / cast number | One number, unique per melt | Must appear on the bundle tag or the packing list |
| Chemical composition | Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti with limits | Each element inside the alloy window for that grade |
| Mechanical properties | Rp0.2, Rm, elongation A50 | Consistent with the temper, not the annealed range |
| Dimensions | Thickness, width, length, quantity | Matches the packing list and the physical bundle |
| Signature | Producer plus inspection representative | A photocopy without a signature block is not a 3.1 |
EN 10204 defines the certificate types: 3.1 is issued by the manufacturer's authorised inspection representative, 2.2 by the manufacturer alone. A "mill certificate" in an email may be either — the type number is what tells you.
For sheet going into a sign, three matter and the rest is context. Magnesium for 5052 — it is what gives the alloy its strength and its corrosion resistance, and a low magnesium heat will feel softer than the last delivery. Copper as an impurity ceiling in 3003 and 5052, because copper above the limit hurts corrosion resistance at cut edges. Elongation because it tells you whether the sheet will crack when the punch forms a corner.
Tensile strength gets all the attention and matters least on a sign panel, which is stiffness-limited rather than strength-limited. If a panel is failing in service it is almost never because Rm was 5 % low; it is because the panel was too thin, the frame was under-built or the film lifted at an edge.
Stop and document. Photograph the bundle tag, the certificate and the packing list together, note the heat numbers on both, and raise it before the material is cut. Once a panel is punched and laminated, the argument about which heat it came from becomes a commercial negotiation rather than a material claim.
Two practical habits reduce the risk. Ask for the certificate with the pre-shipment documents rather than after arrival, so discrepancies can be fixed while the goods are still at the port of loading. And keep certificates filed by heat number for the retention period your customer requires — three years is the figure we work to, and it is what makes a warranty conversation possible years later.
Certificate by heat, packing list by pallet with heat numbers cross-referenced, and dimensional records for the run. If a project needs a third-party inspection, the certificate pack is what the inspector starts from.
Inspection document types — including 3.1, issued by the manufacturer's authorised inspection representative and traceable to the heat — are defined in EN 10204, "Metallic products — Types of inspection documents", published by CEN. The mechanical property requirements the certificate is checked against come from ASTM B209 at ASTM International or EN 485-2.
Sources: CEN, Brussels · ASTM International, West Conshohocken, PA. Cited 30 October 2026.
No. A mill certificate states that the heat was tested and met the specification; a test report gives the individual test results. EN 10204 3.1 sits between the two — it carries specific values and is signed by an independent inspection representative.
Not always, but ask for one when the project is public infrastructure, when the buyer's specification names a grade, or when you intend to resell the panels with a material declaration. It costs nothing to request at the quotation stage.
It can cover multiple bundles, but each bundle still has to be marked with its heat number so the certificate can be applied to the right metal. A certificate with one heat number covering three different melts is a document problem waiting to happen.
Elongation measured over a 50 mm gauge length, expressed as a percentage. It is the property that predicts whether the sheet will form without cracking at a corner or a tight radius.
Specification questions are answered by the same person who quotes the job.