In the procurement of industrial flanges, fittings, and pressure vessels, a Mill Test Certificate (MTC)—also referred to as a Certified Material Test Report (CMTR)—is the definitive legal and technical pedigree of the product. The European standard EN 10204 (Metallic products – Types of inspection documents) defines the exact hierarchy of documentation, validating who conducted the testing and whether the test results reflect the exact product shipped or merely representative batch data.
EN 10204 classifies test certificates into two broad divisions: Non-specific inspection (Types 2.1 and 2.2) and Specific inspection (Types 3.1 and 3.2):
| Type | Document Title | Test Data Nature | Authorized Validator |
|---|---|---|---|
| Type 2.1 | Declaration of Compliance | No test results included; simple statement of conformity | Manufacturer |
| Type 2.2 | Test Report | Non-specific; representative test results from general mill production | Manufacturer |
| Type 3.1 | Inspection Certificate 3.1 | Specific test results on the exact heat/lot supplied | Manufacturer's independent QC representative |
| Type 3.2 | Inspection Certificate 3.2 | Specific test results verified by independent third party | Manufacturer's QC + Independent 3rd Party (SGS, TUV, Lloyd's) |
An EN 10204 3.1 certificate is the baseline standard demanded by oil & gas operators, EPC contractors, and chemical plants worldwide. To be valid, a 3.1 MTC must contain:
Under an EN 10204 3.2 inspection, the material is witnessed during production and mechanical testing by an independent Third Party Inspection Agency (TPIA) appointed by the purchaser. Common inspecting bodies include:
Specifying 3.2 certification increases inspection costs and delivery lead times by 1 to 2 weeks, and is typically reserved for critical subsea infrastructure, nuclear power piping, lethal gas manifolds, and offshore high-pressure topside systems.
Generally no. Under strict European and ASME rules, a 3.2 certificate requires witnessing of the heat treatment and mechanical testing directly at the manufacturing mill or forging shop. Retrospective 3.2 intent requires exhaustive re-testing, PMI, hardness, and coupon extraction under TPIA witnessing.
It certifies that the material meets both EN 10204 3.1 specific testing rules and NACE MR0175 / ISO 15156 sour service limits—specifically maximum hardness (typically ≤ 22 HRC / 237 HBW) and strict sulfur/phosphorus ceilings to prevent sulfide stress cracking.
Every component manufactured at Remax Forge ships with an authentic EN 10204 3.1 MTC. Third-party 3.2 inspection (TUV, DNV, Lloyd's, SGS, BV) readily accommodated upon order placement.