What is the difference between a 3.1 and a 3.2 material certificate?
EN 10204 sets out the types of inspection document a manufacturer can supply with metallic products. The 2004 edition kept four types, 2.1, 2.2, 3.1 and 3.2, and dropped the older 2.3 and 3.1.A/B/C variants (Wermac). Types 3.1 and 3.2 both report the results of specific inspection on the products actually delivered (or on the same test unit). The difference is who signs off (Material Welding).
| Type | Test results | Who validates it | Typical use in tenders |
|---|---|---|---|
| 2.1 Declaration of compliance | None; statement only | Manufacturer | Low-risk items, non-pressure parts |
| 2.2 Test report | Non-specific (typical) results | Manufacturer | Commodity items, some bolting |
| 3.1 Inspection certificate | Specific results for the delivered material | Manufacturer's authorised inspection representative, independent of the production department | Default for most pressure-containing parts |
| 3.2 Inspection certificate | Specific results for the delivered material | Manufacturer's authorised inspection representative and the purchaser's authorised representative or an inspector named in official regulations | Critical service, sour or low-temperature duty, owner specifications that require third-party validation |
What is EN 10204 3.1 certification?
"3.1 certification" is shorthand for supplying a type 3.1 inspection certificate, often called a mill test certificate or material test report. It is not a certification of your company. It is a document per heat, batch or test unit that states the chemical and mechanical results and the order it relates to, signed by an inspector inside the producing company who is independent of manufacturing.
For a valve, the 3.1 certificates usually come from the foundry, forge or bar mill for each pressure-containing part, plus your own certificate for the assembled valve where the order asks for it. Your deviation list should say which of these you supply.
What does a 3.1 certificate certify?
- That the delivered product meets the order requirements, based on specific inspection and testing.
- The actual test results: typically chemical analysis, tensile properties and, where required, impact and hardness values.
- Traceability to the heat or batch and to the marking on the part.
- That the person validating it is authorised and independent of the production department.
It does not certify that a third party saw the tests. That is what 3.2 adds.
Why a 3.2 requirement matters to the manufacturer
A 3.2 requirement brings a second signatory into your supply chain: the purchaser's authorised inspection representative, or an inspector designated by official regulations, validates the certificate alongside your own inspector (projectmaterials). Depending on the order, that inspector may witness tests at the mill or foundry or review the results before countersigning, so agree the arrangements, notice periods and who pays before you price.
Published sources disagree on how much this adds to cost and lead time, so quote your own figures from your sub-suppliers rather than a rule of thumb (projectmaterials). ValveIQ uses "one overlooked 3.2 material certification requirement" as its main example of a costly tender miss (ValveIQ), which shows how common the problem is.
What to flag in your offer and deviation list
| Check | Where to look | What to flag |
|---|---|---|
| Certificate type required | Project spec, material requisition, ITP, owner standard | 3.2 required where you plan to supply 3.1 |
| Parts covered | Spec clause and ITP | Whether bolting, trim, gaskets and seats are included or only pressure-containing parts |
| Who the 3.2 inspector is | Requisition, ITP | Buyer's inspector, named third party, or your choice from an approved list; who pays |
| Extra tests on the certificate | Spec, datasheet | Impact testing temperature, hardness limits, PMI, corrosion tests that must appear on the certificate |
| Conflicts between documents | Spec vs owner standard vs ITP | Different certificate types in different documents; raise a TQ or a clarification |
| Documentation format | VDRL | Whether certificates go in the final data book, and by when |
A typical deviation row reads: requirement "EN 10204 type 3.2 for pressure-containing parts"; offered "type 3.1"; status Deviation; cost of withdrawal "3.2 available at an added cost and lead time, inspector fees by buyer". See the full worked example in the technical deviation list guide and the datasheet vs specification checklist.
Where OdysseyGPT fits
Certificate requirements are often scattered across the specification, the ITP and the owner standard, which is why they get missed. OdysseyGPT reads the whole package and lists each certificate requirement with the clause and page it came from, for an engineer to check and decide on. See OdysseyGPT for manufacturing.