Material Test Certificate (EN 10204 3.1 / 3.2)
A document issued by the manufacturer of a metallic product that confirms the product complies with the order requirements and reports the results of the tests carried out on it — most commonly an EN 10204 type 3.1 inspection certificate.
A material test certificate (MTC) is the document that travels with a batch of steel, aluminum, or other metallic product to prove what it is made of and how it performs. It confirms that the material complies with the purchase order and the referenced material standard, and it records the actual test results — chemical composition, mechanical properties, and, where relevant, heat treatment and non-destructive testing.
The same document goes by many names. In Europe it is usually called a material certificate, inspection certificate, or simply a “3.1” after the EN 10204 document type it is most often issued as. In North America it is commonly called a mill test report (MTR), mill certificate, mill cert, or certified test report. A mill certificate and a material test certificate are the same thing: a certificate issued by the mill (the material manufacturer) reporting test results for a specific heat or batch.
What Is EN 10204?
EN 10204 is the European standard that defines the types of inspection documents supplied with metallic products — steel plate, bar, tube, forgings, castings, fasteners, and similar. It does not specify what to test or what the acceptance limits are; those come from the product standard (for example EN 10025 for structural steel or EN 10028 for pressure-vessel steel) and from the purchase order. EN 10204 only defines who validates the document and which products the reported results relate to. The equivalent international standard is ISO 10474, which uses the same document types.
The standard distinguishes between non-specific inspection, carried out by the manufacturer according to its own procedures on products that are not necessarily the ones being delivered, and specific inspection, carried out before delivery on the actual products supplied (or on test units of which they form part).
The Four EN 10204 Document Types
| Type | Name | Test basis | Who validates it |
|---|---|---|---|
| 2.1 | Declaration of compliance with the order | No test results | The manufacturer |
| 2.2 | Test report | Non-specific inspection | The manufacturer |
| 3.1 | Inspection certificate 3.1 | Specific inspection | The manufacturer’s authorized inspection representative, independent of the manufacturing department |
| 3.2 | Inspection certificate 3.2 | Specific inspection | The manufacturer’s authorized inspection representative and either the purchaser’s authorized inspection representative or an inspector designated by official regulations |
The difference between 2.x and 3.x documents is whether the results relate to the specific products delivered. The difference between 3.1 and 3.2 is whether a second party, independent of the manufacturer, has countersigned the certificate.
What an EN 10204 3.1 Certificate Contains
A 3.1 inspection certificate is the workhorse of material traceability in regulated manufacturing. A typical certificate includes:
- The manufacturer’s name, the certificate number, and the date of issue
- The purchaser’s order number and the manufacturer’s works order reference
- A product description: form, dimensions, quantity, and delivery condition
- The material grade and the standard it is supplied to (for example S355J2 to EN 10025-2)
- The heat number (also called cast number or melt number) and, where applicable, the batch or lot number
- Chemical composition from the ladle or product analysis, element by element
- Mechanical properties: yield strength, tensile strength, elongation, and impact energy at the specified test temperature
- Heat-treatment condition (normalized, quenched and tempered, solution annealed, and so on)
- Results of any non-destructive testing, hydrostatic testing, or hardness testing that the product standard or order requires
- The marking applied to the product so it can be matched back to the certificate
- The validation: the name, position, and signature (or electronic validation) of the authorized inspection representative
3.1 vs 3.2: When to Specify Each
For most industrial purchasing, a 3.1 certificate is sufficient. It gives specific test results for the delivered material, validated by someone inside the manufacturer’s organization but outside the production line. It is the default expectation for structural steel, pressure-retaining materials, piping, and machined components in ISO 9001-certified supply chains.
A 3.2 certificate is specified when a third party must witness or verify the testing. Typical cases are main pressure-bearing parts under the Pressure Equipment Directive, offshore and subsea structures, nuclear components, lifting equipment, and critical structural members where the purchaser or an authority wants independent assurance. The countersigning party may be a classification society surveyor, a notified body, a purchaser’s inspector, or an inspector designated by official regulations. Because a 3.2 certificate requires an inspector to attend the testing, it costs more and adds lead time, so it is reserved for components where a material failure would be severe.
Under the Pressure Equipment Directive, main pressure-bearing parts require a certificate of specific product control — a 3.1 at minimum, with 3.2 specified where the purchaser, the notified body, or the applicable code requires independent witnessing.
Heat-Number Traceability
The heat number is the thread that ties a material certificate to the physical product. Every melt of steel is assigned a heat number at the mill, which is stamped or stencilled on the plate, bar, or tube and printed on the certificate. As the material is cut, formed, welded, and machined, the heat number must be transferred to each piece so that any finished component can be traced back to its certificate. Auditors under PED, ASME, and ISO 9001 routinely pick a component, ask for its heat number, and expect the matching MTC to be produced.
Common Problems With Material Certificates
- Missing certificates at goods receipt. Material arrives with no MTC, or with a 2.2 test report when the order called for a 3.1, and the gap is discovered months later during an audit.
- Mismatched heat numbers. The heat number on the material does not match the number on the certificate, often because a supplier substituted stock without issuing new paperwork.
- Certificates scattered across email and shared drives. MTCs arrive as PDF attachments from dozens of suppliers and are filed inconsistently, so assembling a documentation pack for a finished assembly means reconstructing it from memory.
- Audit exposure. Under PED, ASME Section VIII, EN 1090, ISO 9001, and customer quality agreements, an inability to produce the MTC for a pressure-retaining or load-bearing part is a non-conformance in its own right.
How Certificate Management Software Helps
Certificate management software gives every MTC a structured home, linked to the supplier that issued it, the heat number it covers, and the products and sub-assemblies that consumed the material. Certificate management makes each 3.1 or 3.2 searchable by heat number, grade, and supplier; supplier collaboration lets suppliers upload certificates directly against the purchase order so nothing arrives by email; and the product library ties certificates to the finished-product hierarchy so that a customer or auditor documentation pack can be assembled in minutes. For manufacturers working under PED, ASME, or ISO 9001, that means the question “show me the MTC for this component” has an immediate answer.
Wer braucht das?
Manufacturers, fabricators, distributors, and end-users of metallic products in regulated industries — pressure equipment, structural steel, piping, oil and gas, offshore, automotive, aerospace, and nuclear.