Confirm EN 10204 3.1 wording during RFQ review
BLD Forge Direct
MTC 3.1 Guide for Forged Flange RFQs
This guide walks through a real EN 10204 3.1 inspection certificate issued by our own laboratory in February 2026, so you can see exactly what a compliant MTC contains, how to verify each block, and what to state in the RFQ so the certificate matches your project.
Summary
This guide walks through a real EN 10204 3.1 inspection certificate issued by our own laboratory in February 2026, so you can see exactly what a compliant MTC contains, how to verify each block, and what to state in the RFQ so the certificate matches your project.
Match heat number, material grade and product marking
Check chemical, mechanical, impact and NDT record needs
State third-party inspection requirements before quotation
Engineering Selection Notes
Most MTC guides describe certificates in the abstract. This one shows a real document: an EN 10204 3.1 inspection certificate our laboratory issued on 25 February 2026 for ten 304L reducing flanges. Only the customer name and order references are redacted - the technical content, stamps and signature blocks are exactly what buyers receive with a shipment.
The single most useful habit when reviewing a 3.1 is to read it against two references at once: the product marking (does the heat number match?) and the material standard (do the measured values sit inside the limits?). On this certificate the mill chemistry and the mechanical results both sit comfortably inside the printed limits, and the test method, revision and temperature are stated - which is what makes the values auditable rather than decorative.
Where buyers get hurt is scope, not forgery: a genuine 3.1 that simply does not cover the dimensional report, PMI or the impact test their project needed. The certificate defines what was tested; the RFQ defines what should be. That is why the checklist below front-loads document scope into the enquiry stage.
First-Hand Evidence
Actual factory documentation, shown with customer identifiers redacted. What you see here is what buyers receive.
Redacted areas cover the customer name and order references only; all technical content is unedited.
Direct Answers with Evidence
Each answer states the conclusion first, then the evidence, the conditions where it applies and its limits.
What makes a certificate a true EN 10204 3.1 document?
A 3.1 certificate is issued by the manufacturer and validated by its own authorized inspection representative who is independent of production, and it must report actual test results of the delivered items, tied to heat numbers.
Evidence
- On the specimen above: the certification statement, the QC inspection stamp and the authorized-representative signature block sit at the bottom of the document
- Every line item carries its heat number (SY2504B217) and test specimen number (26Y020122), which must match the marking on the flange
Applies when
Applies to metallic products certified under EN 10204; the equivalent practice covers ASTM-based orders such as this A182 304L example.
Limits
3.1 is manufacturer-validated. If your project requires validation by a party independent of the manufacturer, specify EN 10204 3.2 in the RFQ - that adds a third-party inspector, cost and lead time.
How do you verify a 3.1 certificate line by line?
Check four blocks in order: identity (heat number vs product marking), chemistry (measured vs standard limits), mechanicals (measured vs standard minimums), and process (heat treatment, standard revision, test method).
Evidence
- Chemistry on the specimen: C 0.020% against a 0.03% max, Cr 18.10% within 18.00-20.00%, Ni 8.01% within 8.00-13.00% - every measured value sits inside the printed limits
- Mechanicals per ASTM A370-24 at 20°C, transverse specimen: yield 264 N/mm² against a 170 minimum, tensile 565 N/mm² against 485, elongation 52% against 30, reduction of area 77% against 50, hardness 156/153/157 HBW
- Process block states solution annealing at 1040±10°C and the governing revision A182/A182M-25
Applies when
Numbers above are from certificate BLD-26-2-25-001 for heat SY2504B217; every heat gets its own measured values.
Limits
A 3.1 does not by itself cover dimensional reports, PMI, UT/MT/PT or third-party witness - those must be ordered separately and are listed as separate documents.
What must the RFQ state so the 3.1 matches your project?
State the certificate type (3.1 or 3.2), material standard with revision, heat treatment condition, any impact/hardness/PMI/NDT requirements, and the language or format your end user expects - before price is agreed.
Evidence
- The specimen shows what is only there because the order asked for it: solution-annealing temperature, forging ratio, transverse test direction
- Our lab issues certificates in English as standard; Russian-format passports are available for CIS projects
Applies when
Best stated in the RFQ line items; adding certification requirements after production may be impossible if extra test material was not reserved.
Limits
A certificate cannot be upgraded from 3.1 to 3.2 retroactively without repeat witness testing, if that is possible at all.
Source Basis
The tables below use public standard-scope notes and buyer document rules, not copied proprietary dimension tables.
- EN 10204 - Metallic products, types of inspection documents (overview) - public overview of certificate types 2.1, 2.2, 3.1, 3.2
- ASTM A182/A182M - forged flange material specification (scope page) - governing standard and revision quoted on the specimen certificate
Measured values vs specification limits - taken from the certificate above (heat SY2504B217, 304L)
| Property | Limit printed on the certificate | Measured value | Verdict |
|---|---|---|---|
| C | max 0.03% | 0.020% | within limit |
| Si | max 1.00% | 0.38% | within limit |
| Mn | max 2.00% | 1.34% | within limit |
| P | max 0.045% | 0.031% | within limit |
| S | max 0.030% | 0.001% | within limit |
| Cr | 18.00-20.00% | 18.10% | within range |
| Ni | 8.00-13.00% | 8.01% | within range |
| N | max 0.10% | 0.066% | within limit |
| Yield strength Rp0.2 (ASTM A370-24, 20°C, transverse) | min 170 N/mm² | 264 N/mm² | passes with margin |
| Tensile strength Rm | min 485 N/mm² | 565 N/mm² | passes with margin |
| Elongation A | min 30% | 52% | passes with margin |
| Reduction of area Z | min 50% | 77% | passes with margin |
| Hardness | - | 156 / 153 / 157 HBW | reported (three readings) |
MTC 3.1 Data Buyers Should Check
| Certificate field | Required evidence | Common mismatch | Buyer action |
|---|---|---|---|
| Heat number | Same heat on forging, marking and MTC | Part marking does not match certificate | Request heat traceability photo/report |
| Material grade | Exact ASTM/EN/GOST grade and condition | A105 supplied where A105N is required | Confirm before production |
| Chemical analysis | C, Mn, Si, P, S and alloy elements | Grade family looks similar but chemistry differs | Review against material standard |
| Mechanical test | Tensile, yield, elongation, reduction where applicable | Missing low-temperature impact record | Add impact requirement in RFQ |
| Heat treatment | Normalizing, Q+T, solution annealing or stress relief | Treatment not listed on MTC | Require heat-treatment record |
| Inspection reference | Dimensional, PMI, UT, MT/PT if specified | Inspection requested after quotation | List inspection scope in first RFQ |
Practical Checklist
Use this list before sending drawings or line items for quotation review.
Required certificate type, such as EN 10204 3.1
Material grade, heat number traceability and product marking
Chemical composition and mechanical test values required by the standard
Heat treatment record, impact test or hardness test if required
Dimensional report, PMI, UT, MT or PT if required by the project
Third-party inspection witness, review or release note
Language, stamp or document format required by your project or end user
Common RFQ Mistakes
These points often cause repeated clarification, price revisions or document mismatch.
- Asking for MTC 3.1 after the order is already priced without documents
- Not matching heat numbers between products, marks and certificates
- Forgetting impact test requirements for low-temperature projects
- Assuming third-party inspection is included without stating it in the RFQ
- Treating a certificate PDF as enough when the project also needs dimensional or NDT reports
FAQ
Short answers for buyers preparing this RFQ topic.
What is an EN 10204 3.1 material test certificate?
A 3.1 MTC is issued by the manufacturer and validated by its own inspection department independent of production. It reports the actual chemical composition and mechanical test results of the delivered heat, linked to the heat number marked on the flange.
What is the difference between MTC 3.1 and 3.2?
3.1 is validated by the manufacturer's internal inspector. 3.2 adds validation by an independent third party (for example Lloyd's, BV or the purchaser's inspector), which increases cost and lead time and should be stated in the RFQ.
What should a buyer check on a received 3.1 certificate?
Match the heat number on the certificate against the marking on the product, check chemistry and mechanical values against the material standard, and confirm heat treatment condition, dimensions standard and any required impact or hardness tests are reported.
Does every forged flange order need a 3.1 MTC?
Most pressure-service and project orders require it, and it is standard practice for export flanges. Requesting 3.1 in the RFQ costs little; adding certification after production may be impossible if traceability was not maintained.
Author & Verification
Written by: Tom Fan, Sales Manager, BLD Forge Direct (Shanxi Baolongda Forging Co., Ltd.)
Reviewed by: BLD QC Engineering Team - in-house CNAS-accredited laboratory, 15 QC engineers
Last verified: 2026-07-17
Revision log
- 2026-07-17 - Added an annotated real 3.1 certificate specimen (issued 2026-02-25, 304L reducing flanges; customer identifiers redacted), the measured-vs-limit data table taken from that certificate, direct-answer evidence units and this accountability block.
- 2026-07-09 - RFQ checklist and FAQ baseline version.
Send your RFQ or drawing directly to BLD Forge Direct.
Email quote@bldforgedirect.com with standard, drawing, material, quantity and inspection requirements.