An RFQ that says "material cert required" without naming the type is unfinished. For industrial valves and pressure parts, the usual answer is an EN 10204 material test certificate (MTC). The two levels that dominate export packages are 3.1 and 3.2 — and they are not interchangeable. This guide covers Material 3.1 vs 3.2: who signs, who witnesses, when EPCs insist on 3.2, and the cost and lead-time impact.
1. What EN 10204 Is (and What It Is Not)
EN 10204 defines types of inspection documents for metallic products — castings, forgings, bar, plate, pipe, and finished pressure-containing parts. It does not design the valve, set ASME Class, or replace a hydrostatic test. It answers one question: how was the material verified, and who stands behind the record.
In valve and pump trading, the MTC usually covers body, bonnet, ball/disc, stem and other pressure-retaining parts. Soft seats, packing and actuators sit outside the same certificate. CE/PED, API monograms or NACE hardness records accompany the MTC — they do not replace it. See PrimeFlow's certifications overview.
2. Material 3.1 vs 3.2 at a Glance
| Factor | EN 10204 3.1 | EN 10204 3.2 |
|---|---|---|
| Who inspects / tests | Manufacturer (authorised inspection representative, independent of production) | Manufacturer plus independent third party (or purchaser's authorised representative) |
| Who validates the certificate | Manufacturer's authorised inspection representative | Manufacturer and the independent inspector (dual validation) |
| Typical content | Heat / cast number, chemical analysis, mechanical properties as specified | Same content, with third-party witness of sampling, tests or document review as agreed |
| Default use | Commercial export, most process packages | Critical tags, owner/EPC witness, high-liability service |
| Cost & lead time | Included in normal mill/valve package (indicative) | Extra fee + scheduling for inspector attendance (indicative) |
3.1 is a manufacturer's declaration supported by their own inspection organisation. 3.2 requires an independent third party (or the purchaser's authorised representative) to participate in verification and validate the document. That difference makes Material 3.1 vs 3.2 a commercial and scheduling decision, not a checkbox.
3. When EPCs Ask for 3.2
Most commercial valve packages ship on 3.1. EPCs and owners push to 3.2 when:
- Critical pressure-containing tags — high-pressure gas, sour service, lethal media, or owner "critical equipment" lists.
- Project ITP / MR — the inspection and test plan or material requisition names EN 10204 3.2 and the third party (or "TPI appointed by purchaser").
- Owner-witnessed materials — oil majors, LNG and similar end-user standards that ban pure manufacturer self-certification on designated heats.
- Re-supply after a fail — PMI or heat-mix incidents often upgrade the next order from 3.1 to 3.2.
A Middle East oil & gas EPC package (PrimeFlow sample case, indicative) commonly mixes levels: utility valves on 3.1, main process isolation on 3.2. For oil, gas and petrochemical duty, align cert level with tag criticality. Specifying API 600 vs API 602 gate valves without stating 3.1 or 3.2 still leaves the document package open.
4. Cost, Lead Time and What Changes in Practice
Upgrading from 3.1 to 3.2 does not change the steel grade. It changes who is in the room and when tests can run:
- Inspector fee — day rate, travel and report charges (buyer-paid, seller-paid, or split — state it in the PO).
- Mill / foundry scheduling — chemical and mechanical tests held or re-run under witness; missed windows add days to weeks.
- Factory release — shipping documents wait on the dual-signed MTC even if assembly and hydro test are done.
- Scope — full witness of mechanical testing versus document review of mill 3.1 plus PMI at the valve shop. Write the scope; "3.2" alone is ambiguous.
Indicative only: for a standard SS316 ball-valve batch, 3.1 is often available from stock mill paper; 3.2 adds fee and a longer materials gate. Larger carbon-steel or special-alloy heats see a bigger delta. Treat cost and days as indicative until factory and TPI quote the heat.
5. How 3.1 / 3.2 Sit with API, PED and the Doc Pack
| Document | Role | Relation to 3.1 / 3.2 |
|---|---|---|
| EN 10204 3.1 / 3.2 MTC | Chemistry & mechanical proof for pressure parts | Core material trail |
| CE / PED | EU pressure-equipment conformity | Supports material evidence; does not replace MTC |
| API 600 / 6D / 608 (as applicable) | Product design & manufacture standard | Product compliance ≠ material cert level — request both |
| NACE MR0175 / ISO 15156 | Sour-service limits & hardness | Often cross-referenced on the MTC |
| Hydro / seat test + PMI | Factory pressure proof / identity check | Separate from EN 10204; still required for release |
On a representative PrimeFlow 3-piece SS316 ball valve (SKU PF-BV-3PC-316-DN50, indicative), the default commercial package is EN 10204 3.1 on body and ball plus hydro/seat reports. Upgrade to 3.2 when the ITP demands third-party validation. Pair with how to select a ball valve so grade, rating and cert level are decided together.
6. What to Write on the RFQ
- Parts covered — body, bonnet, ball/disc, stem.
- Cert type — EN 10204 3.1 or 3.2 (not "mill cert" alone).
- Third party — for 3.2, name the TPI or "purchaser-appointed TPI".
- Witness scope — mechanical testing / sampling / document review / PMI at works.
- Standards stack — design standard (e.g. API 600, ISO 17292), PED if EU, NACE if sour.
- Marking — heat number on body must match the MTC.
If the project allows it, split the BOM: critical tags 3.2, utilities 3.1 — cheaper than blanket 3.2 on every small brass valve.
Frequently Asked Questions
What is the difference between Material 3.1 and 3.2?
Under EN 10204, 3.1 is validated by the manufacturer's authorised inspection representative (independent of production). 3.2 is validated by both the manufacturer and an independent third party (or the purchaser's authorised representative).
Is EN 10204 3.1 enough for most valve orders?
Yes for most commercial process, water and general industrial packages. Move to 3.2 when the EPC/ITP or owner standard requires independent witness.
Does 3.2 change the material grade or only the paperwork?
Only the verification path. The specified grade (e.g. ASTM A351 CF8M / SS316) stays the same; sampling, witness and dual validation change.
Who pays for the third-party inspector on a 3.2 order?
Contract-dependent. State in the RFQ/PO whether TPI costs are buyer-paid, seller-included or shared — and who nominates the agency.
Can I mix 3.1 and 3.2 on one shipment?
Yes. Critical pressure parts on 3.2, utilities on 3.1, if the packing list and ITP map each tag to its cert level.
Next step
State 3.1 or 3.2, the parts covered, and whether a third party is nominated. With medium, pressure and temperature, PrimeFlow will return material and certification options against your ITP.
Request a quotation → View a 3-piece SS316 ball valve