EN 10204 certificates explained: 2.1, 2.2, 3.1 and 3.2
Mill test certificates come in four types under EN 10204. The type decides who checked the material and what the document proves. Here is how to choose the right one.
What EN 10204 does
EN 10204 defines the types of inspection document a manufacturer can supply with metallic products. It does not set the tests themselves; those come from the product standard, such as API 5L or ASTM A105, and from your order. EN 10204 defines who carries out the inspection and who signs the document. It is used worldwide, including on GCC oil and gas projects, where 3.1 and 3.2 certificates are the ones most often requested.
The four document types
| Type | Name | Test results | Validated by |
|---|---|---|---|
| 2.1 | Declaration of compliance with the order | No | The manufacturer |
| 2.2 | Test report | Yes, non-specific: from production, not necessarily the items supplied | The manufacturer |
| 3.1 | Inspection certificate 3.1 | Yes, specific to the items supplied | The manufacturer’s authorized inspection representative, independent of the manufacturing department |
| 3.2 | Inspection certificate 3.2 | Yes, specific to the items supplied | The manufacturer’s inspection representative and the purchaser’s representative, or an inspector named in official regulations |
3.1 or 3.2?
A 3.1 certificate is the usual standard for pressure-containing materials in oil and gas work. It gives actual results for the heat and lot you receive, signed by an inspector who is independent of production.
A 3.2 certificate adds an independent witness, usually a third-party inspection agency appointed by you or your client, who attends the tests and countersigns the certificate. Specify 3.2 when your project specification requires it, typically for critical items, sour service or high-pressure equipment. It adds cost and time, because the inspector must attend tests at the mill, so it needs to be in your enquiry from the start.
What a 3.1 certificate should show
- Manufacturer name and certificate number
- Product standard and grade, and PSL for line pipe
- Heat number, and lot or test unit, matching the marking on the material
- Chemical analysis
- Mechanical test results: tensile, yield, elongation, and hardness or impact where required
- Heat treatment condition
- Hydrostatic and non-destructive test results where the standard requires them
- Statement of compliance and the inspector’s signature
Certificates for common products
| Product | What to expect |
|---|---|
| Line pipe and OCTG | A 3.1 certificate from the pipe mill, by heat and test unit |
| Flanges and fittings | A 3.1 certificate from the forging or fitting manufacturer, showing heat treatment |
| Valves | Material certificates for pressure-containing parts, plus pressure test certificates to the valve standard |
| Stud bolts and nuts | A 3.1 certificate for the bar or the finished bolting, and for any coating |
Warning signs
- Heat numbers on the certificate do not match the marking on the material
- The certificate is issued by a trader instead of the manufacturer
- Test results are missing, or the certificate only states compliance
- The grade, size or standard differs from your purchase order
- The copy is unclear or looks edited
Older certificate types
Before 2004 the standard used types 3.1.A, 3.1.B, 3.1.C and 3.2. The old 3.1.B became today’s 3.1, while 3.1.A, 3.1.C and the old 3.2 became today’s 3.2. A specification that still asks for 3.1.B means a 3.1 certificate.
Checking certificates on receipt
Match the heat number stamped or stencilled on each item to a certificate, check the standard and grade against your order, and read the test results rather than only the signature. Certificates should arrive with the material, or before it.
Frequently asked questions
Is a mill test certificate the same as an EN 10204 3.1 certificate?
Usually. "Mill test certificate" is the everyday name for the inspection document a mill issues. Most are issued as EN 10204 3.1, but check the type stated on the certificate.
Who validates a 3.2 certificate?
It is validated jointly by the manufacturer’s inspection representative and either the purchaser’s representative or an inspector designated by official regulations.
Can a stockist issue a 3.1 certificate?
The certificate comes from the manufacturer. A stockist should pass on the original, or a certified copy, and keep the material traceable to it.
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