EN 10204 3.1 vs 3.2 MTC for Valve Projects: What to Specify
Technical guide · Supreme Valves India · Updated 2026-10-24
Almost every valve RFQ we receive for export asks for "MTC as per EN 10204 3.1", and a growing number ask for 3.2. The two look similar on paper but they differ in who signs them, when the inspection has to happen, and how much time and cost they add. Getting this right at enquiry stage avoids the most common documentation hold at final inspection.
What EN 10204 actually defines
EN 10204:2004 is a short standard that defines types of inspection documents for metallic products. It does not set test methods or acceptance values; those come from the material specification (for example ASTM A216 for WCB castings or ASTM A105 for forgings). It defines four document types:
| Type | Name | Results based on | Validated by |
|---|---|---|---|
| 2.1 | Declaration of compliance with the order | No test results | Manufacturer |
| 2.2 | Test report | Non-specific inspection (typical production results) | Manufacturer |
| 3.1 | Inspection certificate 3.1 | Specific inspection of the supplied material | Manufacturer's authorised inspection representative, independent of production |
| 3.2 | Inspection certificate 3.2 | Specific inspection of the supplied material | Manufacturer's representative and the purchaser's inspector, or an inspector designated by regulation |
The key word is specific. A 3.1 or 3.2 certificate reports results from the heat or lot that was actually supplied, not typical values. That is why heat number traceability from the casting or forging to the finished valve matters so much.
Which valve parts the certificate covers
Unless the order says otherwise, valve MTCs cover the pressure-containing and pressure-controlling parts: body, bonnet or cover, and on many specifications the closure member (wedge, disc or ball) and the stem. Bolting is often certified separately to ASTM A193 / A194. Soft parts such as PTFE seats, graphite packing and gaskets normally get a certificate of conformity rather than a 3.1.
If your project specification wants 3.1 certificates for trim, bolting or welding consumables as well, state it in the RFQ. It changes how the valve is sourced and inspected, and it is much easier to quote correctly at the start than to add later.
3.1 in practice
For a typical WCB gate valve or CF8M ball valve, a 3.1 certificate shows the chemical analysis and mechanical test results (tensile strength, yield strength, elongation, reduction of area, and impact values where the material specification or the order requires them) for each heat, plus heat treatment condition. The body and bonnet are marked with the heat number so the certificate can be matched to the valve.
A 3.1 is enough for most refinery, petrochemical, water, power and chemical plant service. It is also what the European Pressure Equipment Directive requires for the main pressure-bearing parts of equipment in categories II to IV.
When a project asks for 3.2
We see 3.2 requested mainly in these cases:
- Offshore and subsea packages, and projects that follow NORSOK or similar operator specifications.
- Sour service and other critical hydrocarbon service where the client's material specification calls for witnessed testing.
- Duplex, super duplex and nickel alloy valves, where ferrite content, corrosion testing (for example ASTM G48) and impact testing are part of the acceptance.
- Equipment where a regulation or a notified body designates the inspector.
The second signature on a 3.2 comes from the purchaser's authorised inspector or a third-party inspection agency nominated by the purchaser. That inspector has to witness the material tests, or at minimum verify them on the actual test pieces, before the certificate is issued.
What 3.2 changes in schedule and cost
- Timing. The witness has to happen at the foundry or forge shop when the test bars are pulled and tested. The inspection agency must be appointed and the inspection test plan agreed before casting or forging starts.
- Cost. The purchaser or the supplier pays the inspection agency's visit charges. For small quantities this can be a large share of the order value.
- Lead time. Expect extra time to coordinate visits and get the agency's stamp on the certificates. Ordering from stock usually isn't possible, because stock material was not witnessed.
How to specify it in the RFQ
A clear line in the enquiry saves a round of clarification. For example:
Material certificates: EN 10204 3.1 for body, bonnet, disc/ball and stem, with heat number traceability. Valve test certificate to API 598. 3.2 not required.
If you need 3.2, name the inspection agency (or say who will appoint it), list the parts it applies to, and state whether the inspector must also witness the valve pressure tests. Those are separate hold points.
Common mistakes we see
- Asking for "3.2 MTC" when the real need is third-party witness of the final pressure test. That is a TPI requirement on the valve test, not a 3.2 material certificate.
- Expecting stock valves to come with 3.2 certificates.
- Not stating which parts need certificates, so the quotation and the final dossier don't match.
- Accepting certificates where the heat number on the body casting doesn't appear on the MTC.
Send the project's material and inspection requirements with your line list and we will confirm what can be supplied from stock with 3.1 and what needs a witnessed production route.
Frequently asked questions
Is an EN 10204 3.1 certificate enough for most valve orders?
Yes. For general refinery, water, chemical and utility service, a 3.1 certificate for the pressure-containing parts, issued by the manufacturer's independent inspection department and traceable by heat number, is the normal requirement. A 3.2 is only needed when the purchase order, the project specification or a regulation explicitly asks for it.
Can a 3.1 certificate be upgraded to 3.2 after the valves are made?
No. A 3.2 certificate requires the purchaser's inspector or a nominated third-party inspector to witness or verify the tests on the actual material. If that witness was not present when the castings, forgings or test bars were tested, the certificate cannot be converted afterwards. It must be ordered before production starts.
Does the MTC replace the valve test certificate?
No. The MTC covers the material of the body, bonnet and other parts. The valve test certificate records the shell, seat and backseat tests on the finished valve, usually to API 598 or EN 12266-1. A complete dossier normally contains both, cross-referenced by serial number and heat number.
Related products & guides
Continue to RFQ
Contact / RFQ form · Quotation checklist · EPC supplier · AEO SEO GEO hub
Project RFQ: EPC · Fire · How to buy · Lead hub · Contact / RFQ