A certificate is not proof. Here is what to check.
Ask a supplier for certification and you will get a PDF. The PDF is the beginning of the check, not the end of it. Three questions separate evidence from decoration: who issued it, what scope does it actually cover, and does it name the batch you are buying.
There is no such document as a CE certificate.
CE marking is the manufacturer's own legal declaration that a product meets the applicable European requirements. It is not awarded by an authority and there is no certificate that says CE on it, which is why a supplier offering you one is a warning rather than a reassurance.
Where a Notified Body is involved in the assessment, its four-digit identification number appears alongside the mark. That number is checkable. What you should be asking for is the Notified Body's certificate for the factory's production control, plus the Declaration of Performance for the actual product you are buying.
- Ask for the Declaration of Performance, not for a CE certificate.
- Where a Notified Body applies, look for its four-digit number and verify the body.
- A mark applied by a factory with no audited production control is paper only. It is a known export failure mode.
- The Declaration of Performance must relate to the product and its declared performance, not to the company in general.
EN 1090 shows what real compliance looks like.
For structural steel and aluminium going into European work, EN 1090 applies under the Construction Products Regulation. Genuine compliance is a system rather than a document: an audited Factory Production Control certified by a Notified Body, welding management to ISO 3834 with qualified welders and approved procedures, and a Declaration of Performance for the specific project.
EN 1090-1 governs conformity assessment and marking, EN 1090-2 is the technical execution reference, and Execution Classes EXC1 to EXC4 scale the rigour to the consequence of failure. If nobody has told you which Execution Class applies, that conversation has not happened yet.
Q355B is not simply S355JR with a different name.
Chinese manufacturers certify to GB and GB/T national standards, and some categories additionally require CCC, China Compulsory Certification. Where your specification names a European or American grade, the question is whether the mill can certify to it, not whether an equivalent exists on a comparison chart.
Structural steel is the clearest example. Q355B to GB/T 1591 is the usual counterpart to S355JR under EN 10025, and GB/T 1591 carries mandatory impact-energy requirements that the older GB/T 700 does not. Two grades with similar names can therefore arrive with materially different evidence behind them.
- Confirm which standard the mill certificate is issued against, not just the grade name.
- Check whether impact-energy testing is included, and at what temperature.
- Where CCC applies to the category, confirm it covers the exact model.
- Treat equivalence tables as a starting point for a question, never as an answer.
Each category has a document buyers actually check.
Beyond steel, the pattern repeats: one anchor standard defines classification or qualification, and a second defines the test methods or the safety case. The certificate is only useful when it is tied to the exact model and its bill of materials.
Depth varies by category, and per-product detail is worth verifying at enquiry rather than assumed from the category.
- Scaffolding: EN 12810 and EN 12811 for facade systems and structural design.
- Ceramic tiles: ISO 13006 for classification by water absorption and shaping, with test methods in ISO 10545.
- Solar modules: IEC 61215 for design qualification and IEC 61730 for safety, tied to the exact model and bill of materials.
- Metals generally: EN 10204 for the certificate type, GB or GB/T where the mill is Chinese.
Who issued this and are they accredited to do so. What scope does it cover, the company, the product family, or this product. And does it name the batch, heat or serial range that is in my container. A certificate that survives all three is evidence. One that does not is a document.