Mill test certificates: 3.1, 3.2 and why it matters on site
EN 10204 defines what a material certificate actually proves. The difference between 3.1 and 3.2 decides whether material is accepted.
A mill test certificate is the document that links the physical material in front of you to a tested heat of steel. Without it, a grade marking is just an assertion. EN 10204 is the standard that defines what different certificate types actually guarantee.
The types that matter
| Type | What it is | Who signs it |
|---|---|---|
| 2.1 | Declaration of compliance. No test results. | The manufacturer |
| 2.2 | Test report with non-specific test results. | The manufacturer |
| 3.1 | Test results from the actual batch supplied. | The manufacturer's authorised inspection representative, independent of production |
| 3.2 | Test results from the actual batch, witnessed independently. | Both the manufacturer and an independent inspector or the purchaser |
Scroll the table horizontally to see all columns.
What 3.1 gives you
A 3.1 certificate reports the chemical composition and mechanical properties of the specific heat your material came from, and is signed by someone at the mill who is organisationally independent of the production department. It carries the heat number, which appears on the material itself. This is the standard for most industrial supply and it is what Rajgranth issues by default.
When you need 3.2
A 3.2 certificate adds independent witnessing — a third-party inspection body, or the purchaser's own inspector, physically present for the testing. It is typically required for pressure equipment under PED, for nuclear and offshore work, and wherever a client specification or regulatory regime demands it.
Reading one properly
- Heat number — must match the marking stamped on the material
- Chemical composition — check it against the grade specification, not just the grade name
- Mechanical properties — tensile, yield, elongation, hardness
- The specification the material was made to, e.g. ASTM A312 TP316L
- Any supplementary tests: intergranular corrosion, hydrostatic, PMI
- The signature and the authority of whoever signed it
Products covered
Specifying for a live project?
Send the service conditions and we will tell you what we would specify, and what we hold.