Steel Pipe Mill Certificate: How to Read and Verify It

A mill test certificate is the document that connects a bundle of steel pipe to the heat of steel it was made from and to the test results that prove it meets the standard. The certificate is only useful if the buyer checks the heat number, the chemistry, the mechanical results and the certificate type against the order.

What an MTC should contain

Manufacturer Producing mill and inspection department.
Heat number The number that links the pipe to the cast and the test results.
Specification Standard and grade, for example API 5L X65 PSL2 or ASTM A106 Grade B.
Dimensions Outside diameter, wall thickness, length and quantity.
Chemistry Heat or product analysis results against the standard limits.
Mechanical results Yield, tensile, elongation, impact and hardness where required.
Tests performed Hydrostatic, non-destructive examination and any supplementary tests.
Certificate type EN 10204 2.1, 2.2, 3.1 or 3.2.

The first check is the heat number

Every certificate is only as good as the traceability behind it. Check that the heat number on the certificate matches the number stencilled on the pipe or bundle and the packing list. A certificate with results that cannot be matched to the material on site is not proof; it is a document that describes something else.

Certificate types: 3.1 and 3.2

Type	Who signs	What it means for the buyer
EN 10204 3.1	Mill inspection department independent of production	Specific test results from the supplied product, traceable to the heat
EN 10204 3.2	Mill results countersigned by a nominated third-party inspection agency	Independent verification of the tests and traceability

A 3.2 certificate cannot be created after delivery from a 3.1 certificate. The third-party inspector must witness or verify the testing during production, so 3.2 must be specified when the order is placed.

Route of an EN 10204 certificate: the tested heat and the mill inspection department issuing a 3.1, and the nominated third party whose countersignature makes it a 3.2 — The 3.1 comes from the mill’s own inspection department; the 3.2 is the same results countersigned by a third party. Source: this article’s certificate type table.

Common problems and how to prevent them

Heat number mismatch Reject the lot or hold it for identification before any cutting or mixing.
Certificate type changed The order and the certificate must state the same EN 10204 type.
Wrong grade A105 and A105N are not the same; the full grade and delivery condition must appear.
Missing supplementary tests CVN, HIC, SSC, hardness or PMI results must be present if the order called for them.
Results outside limits Check each result against the standard, not against memory.

What to write on the purchase order

Certificate type EN 10204 3.1 or 3.2.
Third-party agency Named agency if 3.2 is required.
Supplementary tests Impact temperature and energy, hardness limit, HIC/SSC, PMI or coating tests.
Marking Heat number, size, grade and any project identification.

Where to go next

Need to verify a steel pipe certificate? Send the standard, grade, outside diameter, wall thickness, length and quantity, and we will reply with availability and pricing.

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