Mill Test Certificates Explained: EN 10204 2.1, 2.2, 3.1 and 3.2
How to read a steel mill test certificate (MTC): EN 10204 types 2.1, 2.2, 3.1 and 3.2, heat numbers, chemistry, mechanical properties, and red flags to watch for.
Saudi Steel Work Editorial Team · · 3 min read
Short answer: A mill test certificate (MTC) documents the chemical composition and mechanical properties of a specific heat of steel and links it to the product by heat number. EN 10204 defines four document types: 2.1 (declaration of compliance), 2.2 (non-specific test report), 3.1 (specific test results validated by the manufacturer's independent inspector) and 3.2 (3.1 plus validation by a third party or purchaser's representative).
The mill test certificate is the single most important quality document for steel. Knowing how to read it protects you from accepting the wrong material.
EN 10204 document types
| Type | Name | Contains | Validated by |
|---|---|---|---|
| 2.1 | Declaration of compliance | Statement only | Manufacturer |
| 2.2 | Test report | Non-specific (typical) results | Manufacturer |
| 3.1 | Inspection certificate | Specific results for delivered product | Manufacturer's authorised independent inspector |
| 3.2 | Inspection certificate | Specific results | Manufacturer's inspector and purchaser's or third-party inspector |
What a 3.1 certificate should show
- Manufacturer name and certificate number
- Purchaser and order reference
- Product description and dimensions
- Standard and grade (e.g. EN 10025-2 S355J2+N)
- Heat (cast) number
- Chemical analysis (C, Mn, Si, P, S and alloys; carbon equivalent)
- Mechanical tests: yield, tensile, elongation
- Impact test results and temperature, if required
- Other tests: UT, bend, hardness, hydrotest
- Delivery condition (as-rolled, normalised)
- Signature/stamp of the authorised inspector
How to check it
- Match the heat number on the steel to the certificate
- Confirm standard and grade match your order
- Compare chemistry and properties against the standard's limits
- Check thickness range — properties depend on thickness
- Verify certificate type matches your requirement
Red flags
- No heat number, or heat numbers that don't appear on the steel
- Certificates from a different mill than the supplier stated
- Identical results across many different heats
- Missing impact results where a J0/J2 grade was ordered
- Altered or retyped documents
When in doubt, ask the supplier to obtain verification from the mill, or arrange independent testing.
Traceability through fabrication
Fabricators transfer heat numbers to cut pieces so every finished member traces back to its certificate (fabrication process).
Related: documents to request from steel suppliers and quality and standards.