What a Mill Test Certificate Really Certifies on a Steel Order

Every steel shipment arrives with a certificate, and almost nobody reads past the grade line. That single page is the only proof that the steel in the container is the steel you paid for — and it can be perfectly genuine while still failing you at destination. Here is what an EN 10204 3.1 certificate must contain, which fields carry the weight, and the four traps that quietly turn a valid document into an unenforceable one.

Two documents that look identical and are not

A mill test certificate arrives as one or two pages of dense tables, printed on mill letterhead, stamped and signed. Buyers treat them as a formality because they always look the same. They do not mean the same thing. The EN 10204 standard defines several inspection document types, and the number in the corner of the page tells you how much of that page is actually about your steel.

The distinction that matters commercially is 2.2 versus 3.1. Both are called a mill certificate in everyday trade. Only one is a test report on your steel. If your purchase order says 3.1 and the page you receive says 2.2, the document is not late or incomplete — it is a different product, and it will be rejected by any inspector who reads the corner of the page.

The fields that carry the weight

Certificates from different mills look wildly different, but the enforceable content is a short list. If any of these five is missing, the document cannot do its job.

A certificate that carries these five fields, correctly, is worth more than a folder of documents that carries everything else.

Four traps that void an otherwise valid certificate

1. Typical values presented as test results

The most common failure is not forgery. It is a mill datasheet — the generic table of typical chemistry and guaranteed minimum mechanicals for that grade — printed on the same letterhead and signed the same way. It looks like a test report because it has the same column headers, but the numbers describe the grade in general, not the heat in your container. The tell is a column that reads typical or min with no individual test values, and a heat number that appears nowhere on the page.

2. One certificate for a mixed bundle

Market-supplied steel is often consolidated. A bundle of angles can hold pieces from two heats, and a container can hold material from three mills. One certificate then arrives for the shipment and gets filed as if it covers everything. On arrival, an inspector picks a piece, reads the stencil, and finds a heat number that is not on the certificate. The practical fix is procedural: the certificate must list every heat number in the shipment, and the bundle tags must match that list one for one.

3. Grade on the certificate does not match the grade on the order

This is where a substitution that was never discussed becomes visible. A certificate for Q235B against a purchase order for S235JR is not a small deviation; it is a documented failure, and it hands the buyer an argument the supplier cannot win. The reverse also happens: the certificate is right and the purchase order was vague. Both sides then negotiate over a document that should have been settled at enquiry stage. Our comparison of Q235, S235JR and A36 covers how to write the grade so this cannot occur.

4. The certificate covers the coil, not the cut piece

Once material is cut to length, drilled or bent, the piece loses its stencil. A certificate that traces to a coil is of limited use when the delivered items are 6 m cut lengths with no marking. Where the supplier performs the processing, the traceability has to be re-established after cutting: a tag on each bundle carrying the original heat number and the certificate reference. Without that tag, the paperwork describes material nobody can identify.

A twenty-minute check before you release the balance

1. Read the document type first. Confirm 3.1, not 2.2, if the order asked for specific inspection.
2. Match the standard and grade character by character against the purchase order, including the year of the standard.
3. Check the heat numbers against the packing list and the bundle tags. Count them. If there are fewer heat numbers than bundles, ask which bundle is unaccounted for.
4. Look for actual values, not typicals. If every chemistry row reads the same across two different heats, you are reading a datasheet.
5. Verify elongation is present alongside yield and tensile, with the gauge length stated.
6. Confirm the issue date precedes the shipment date, and that the signatory block is complete rather than a scanned signature pasted over a blank line.

None of this requires a laboratory. It requires fifteen minutes and the willingness to send the certificate back before the container is booked, rather than argue about it after the steel is on site.

What to write on the purchase order

How this is handled on our side

As a market supplier in Foshan we buy across several domestic mills, so a single order can genuinely involve more than one heat. The rule we work to: the certificate is collected per heat, checked against the grade on the quotation, and scanned to the buyer for approval before the container is closed. Where an order is cut to length, bundles are re-tagged with the original heat number and certificate reference after cutting, because a 6 m cut length with no marking is untraceable no matter how complete the paperwork. Sections supplied on this basis include hot rolled steel plate, equal angle steel and galvanized square tube.

Certificate type, grade designation and inspection requirements are confirmed against each purchase list and the project specification. This article describes standard trade practice for orientation and is not an engineering or inspection ruling.

Send the specification, not just the size list

If your project or your customer names a certificate type, a standard year or a third-party inspector, put it in the enquiry. We will confirm what can be certified against that specification, and what the documents will show, before anything is cut. Send your purchase list →