Standards & specifications
How to Read a Mill Test Certificate (MTC): EN 10204 Types and a Delivery Checklist
What a mill test certificate contains, how EN 10204 types 2.1, 2.2, 3.1 and 3.2 differ, and what to check against it when rebar or plate arrives.
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Contents
Most steel deliveries arrive with a document that few people on site read closely: the mill test certificate (MTC). It is the document that shows the steel you received is the grade and quality you ordered. This guide explains what an MTC is, how the certificate types in EN 10204 differ, and what to check against the certificate when a delivery of rebar or plate arrives.
What a mill test certificate is
Wikipedia describes a mill test report as a quality assurance document that certifies a material's chemical and physical properties and gives the end user traceability and assurance about the quality of the steel. It is also called an MTC, a mill test report (MTR) or an inspection certificate. According to Projectmaterials, MTC and MTR are used interchangeably, with MTC more common on European and international projects.
EN 10204 and the four certificate types
The type of document is defined by EN 10204. Its listing at the Estonian Centre for Standardisation and Accreditation (EVS) shows the 2004 edition, valid since January 2005, which "specifies the different types of inspection documents" supplied to the purchaser, in accordance with the order, for metallic products such as plates, sheets and bars. It does not set the properties of the steel itself; it is used together with the product standard. DIN lists a revision project for the standard started in 2021, with no target date, and the EVS page lists no edition newer than 2004.
| Type | Name | Validated by | Test results |
|---|---|---|---|
| 2.1 | Declaration of compliance | Manufacturer | None |
| 2.2 | Test report | Manufacturer | Non-specific (typical values) |
| 3.1 | Inspection certificate | Manufacturer's inspection representative, independent of manufacturing | Specific to the supplied batch |
| 3.2 | Inspection certificate with third-party validation | Manufacturer's representative plus the purchaser's inspector or one designated by regulations | Specific, witnessed by a third party |
Wikipedia calls the 3.1 the most common type, used when the customer does not require third-party inspection or witnessing. The practical point for a buyer: only 3.1 and 3.2 certificates report the tests of the steel actually delivered.
What is on the certificate
Projectmaterials lists the usual contents of a complete MTC:
- Header and order details: manufacturer, certificate type, date, customer, purchase order reference and product standard.
- Product description: product type, manufacturing process, dimensions, quantities or weights.
- Heat number: the "unique identifier for the steel melt".
- Chemical composition: element percentages per heat against the specification limits.
- Mechanical properties: tensile strength, yield strength, elongation, hardness and impact values where required.
- Heat treatment or condition of supply.
- Marking and validation: product marking details and QA signatures, plus third-party signatures on a 3.2.
The heat number is assigned at melting and carried through the semi-finished product, the finished product, shipping documents and installation records. If cutting removes the original marking, the heat number has to be transferred to the new piece first.
Delivery checklist
- Grade and standard match the purchase order exactly. In the Ahan Assa catalog, for example, A3 (Aj400) ribbed rebar is listed to INSO 3132 and S235JR hot-rolled plate to EN 10029; the certificate should state the same.
- Chemistry is within the product standard's limits; for welded parts also check the carbon equivalent (see our S235JR vs S355JR sheet comparison).
- Mechanical values meet the specified minimums and maximums.
- Heat number on the certificate matches the product label or marking.
- Certificate type and signatures are what the order asked for.
Projectmaterials also advises confirming authenticity with the producing mill when only a digital copy is available.
Specify the certificate in the order
Because EN 10204 ties the document type to the order, the time to decide is before you buy. If the engineer requires a 3.1, or third-party inspection under a 3.2, state it in your quotation request together with grade, standard and dimensions. Our rebar buying guide covers the other order details.
To request a quotation with the certificate you need, use our contact form.
Summary
An MTC certifies the chemistry and mechanical properties of the steel supplied, and EN 10204 defines its type. Types 2.1 and 2.2 carry no results from your own batch; a 3.1 does, validated by the producer's independent inspection staff, and a 3.2 adds a third-party signature. On delivery, match grade, chemistry, mechanical values and above all the heat number, and write the required certificate type into the order from the start.
Frequently asked questions
What is a mill test certificate (MTC)?
It is a document issued by the steel producer that certifies the chemical composition and mechanical properties of the product supplied. It is usually issued to EN 10204 and states the certificate type, the steel grade and the test results.
What is the difference between a 2.2 and a 3.1 certificate?
A 2.2 test report gives non-specific results: typical values, not tests on the batch you received. A 3.1 inspection certificate gives specific results measured on the supplied batch, validated by the producer's inspection representative, who is independent of the manufacturing department.
What is the heat number for?
The heat number is the unique identifier of a steel melt and links the product to that melt's test results. On delivery, the heat number on the product label or marking should match the one on the certificate.
When is a 3.2 certificate needed?
When the purchaser or project regulations require third-party inspection. Besides the producer's inspection representative, a 3.2 is signed by the purchaser's authorised inspector or one designated by official regulations. The certificate type should be written into the purchase order.
Sources
- EVS-EN 10204:2004 Metallic materials - Types of inspection documents — Estonian Centre for Standardisation and Accreditation (EVS)
- DIN EN 10204 rev. — Metallic products - Types of inspection documents (standards project) — DIN
- Mill test report — Wikipedia
- Mill Test Certificates: EN 10204 2.1, 3.1, 3.2 — Projectmaterials
- Ahan Assa public product catalog: grades, standards and order units — Ahan Assa
By Ahan Assa Editorial Team
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