How to Read an EN 10204 3.1 Material Test Certificate

EN 10204 3.1 certificates are required on every shipment of pipe fittings for process plants — but many procurement engineers have never been shown what the document must contain and how to verify it. Here is what to check line by line.

What EN 10204 3.1 Means

EN 10204 is a European standard for inspection documents for metallic products. It defines four document types. Type 3.1 means: a test report issued by the manufacturer's own authorised inspection representative (AIR), independent from the manufacturing department and authorised to issue certificates. The AIR countersigns the certificate — their name and title must appear on the document. This is the minimum acceptable for most process plant piping and for PED Category I and II.

What Must Appear on the Certificate

Product description: Fitting type, nominal size, wall schedule, standard (EN 10253-2 Type B or ASME B16.9), and material grade with EN Werkstoffnummer (e.g. 1.4404) or ASTM designation (e.g. WP316L).
Heat/cast number: The unique identifier for the melt from which the material was made. This is the traceability link — if you receive material, you can trace it to its original heat at the mill.
Heat chemical analysis: All element percentages as measured. Compare against the standard specification (e.g. EN 10272 Table 1 for 1.4404 requires C ≤0.030%, Si ≤1.0%, Mn ≤2.0%, Cr 16.5–18.5%, Mo 2.0–2.5%, Ni 10.0–13.0%). Any element outside specification range is a non-conformance.
Mechanical properties: Tensile strength (UTS), 0.2% proof strength (Rp0.2), elongation (A%), and for impact-tested items, Charpy V-notch energy (J) at the test temperature. Compare against minimum requirements in the standard.
Heat treatment condition: For stainless steel: solution annealed + quenched. For CrMo alloy steel: normalised and tempered, plus PWHT temperature and hold time.
Authorised inspection representative: Name, title, signature, and date. Without a countersignature from an independent AIR, the document is a 2.2 test report — not a 3.1 certificate.
Statement of conformity: The certificate must explicitly state that the product conforms to the order and the applicable standard. A certificate listing test results without a conformity statement is non-compliant.

Common Certificate Defects to Reject

Missing countersignature by AIR — makes it a 2.2 document, not 3.1
Certificate dated before the fittings were ordered — indicates a generic or reused certificate
Heat number on certificate does not match heat number on fitting marking
Chemical analysis shows elements without a comparison to the specification limits
Grade listed as "SS 316" or "AISI 316" without the ASTM or EN material designation
No proof strength (Rp0.2) — tensile only is insufficient for pressure design verification

3.1 vs 3.2 — When You Need Third-Party Countersignature

EN 10204 3.2 adds countersignature by an independent third party (TÜV, Bureau Veritas, Lloyd's Register, DNV) in addition to the manufacturer's AIR. This is required for: PED Category III and IV equipment, nuclear applications, certain offshore codes (DNV-ST-F101), and wherever the project specification explicitly states "3.2". Upgrading from 3.1 to 3.2 requires the TPI to witness the testing — you cannot add a third-party stamp to an existing 3.1 retrospectively.