Steel Pipe Mill Test Certificates: EN 10204 3.1, 3.2 & What Buyers Should Check
For steel pipe buyers, the mill test certificate (MTC, sometimes called the material test certificate or inspection certificate) is the single most important document in the order. It proves the pipe meets the standard and grade you paid for. Yet many importers never read them carefully. Here is how to check one properly.
What Is a Mill Test Certificate?
An MTC is a document issued by the pipe manufacturer (or a nominated inspection body) that records the results of chemical and mechanical tests performed on the batch from which your pipe was produced. It links your pipe to a specific heat number so every length is traceable back to the original steel.
EN 10204 Certificate Types
The European standard EN 10204 classifies certificates by who issues them and how much verification is involved:
| Type | Issued by | Verification | Typical use |
|---|---|---|---|
| 2.1 | Manufacturer, declaration only | None (no results) | Non-critical, low-risk supply |
| 2.2 | Manufacturer, with test results | Mill’s own testing | General structural use |
| 3.1 | Manufacturer, inspected by an independent authority | Mill test results confirmed by third party | Pressure pipe, boiler tube, oil & gas |
| 3.2 | Mill + independent inspection body, jointly | Both parties witness/verify results | Highest assurance, critical service |
For pressure-bearing applications — boiler tubes, oil and gas line pipe, hydraulic cylinders — buyers almost always require a 3.1 certificate, and often 3.2 for critical projects.
Key Items to Verify on an MTC
When you receive a certificate, check at least the following:
- Purchase order reference and batch/heat number — must match the pipes you actually received
- Product description — standard, grade, size (OD × WT) must match your order
- Chemical composition — C, Mn, P, S, Si (and alloying elements) within the standard’s limits
- Mechanical properties — yield, tensile and elongation meet the grade minimums
- Supplementary tests — hydrostatic, UT/ET, impact tests as required
- Signature and stamps — issued by the correct authority (for 3.1, an independent inspection body; for 3.2, joint signature)
- Date of issue — should be close to the shipment date, not weeks before production
Red Flags to Watch For
- Composition values that exactly repeat the standard’s minimums on every single test (real test results vary)
- A certificate without a heat number or with a heat number that does not appear on the pipe stamps
- Certificates from a “trading company” rather than the actual mill
- Test values that do not match the standard, or an EN 10204 3.1 certificate without a third-party inspection body named
How to Require the Right Certificate in Your Order
State it explicitly in your inquiry and purchase order:
Certificate: EN 10204 Type 3.1, issued by an independent inspection body approved by buyer. Third-party inspection: SGS/BV/TUV, witness at mill.
Confirming this in writing prevents disputes and protects your project if something fails later.
Traceability on the Pipe Itself
Your certificate should be backed up by physical traceability: each pipe is stenciled with the heat number, size and grade. Ask for photos of the stenciling as part of the inspection report, and spot-check them on arrival.
If you need help reviewing an MTC before you approve payment, send it to our engineers — we review hundreds of certificates every month and can tell you in minutes whether it is genuine and complete.
