TSG31-2025 requires retesting the mechanical properties of materials with foreign grades. How should this retesting be carried out, and what are the specific standards to be followed?

This is indeed a rather professional question. TSG31-2025 is a safety technical specification for special equipment; for the retesting of materials of foreign brands, mechanical property tests are usually carried out in accordance with the corresponding material standards (such as ASTM, EN, ISO, etc.) as well as domestic conversion standards (such as GB/T 150, GB/T 20878, etc.). Specific recommendations: First, determine whether there is a corresponding domestic grade or relevant national standard for the foreign grade in question. The re-test items generally include tensile testing, impact testing, bending testing, etc. The sampling and testing methods can be referenced according to GB/T 228.1, GB/T 229, and similar standards ； If your organization has the authority, you can also conduct re-inspection in accordance with foreign material standards (such as ASTM A370), but it is necessary to indicate the basis in the inspection report ； It is advisable to consult the relevant provisions on material re-inspection in the original TSG31-2025 document, or to seek advice from local special inspection agencies or certification bodies, in order to avoid non-compliance due to differences in the interpretation of the standards. It is recommended to find the standard original text or consult experienced colleagues before proceeding with actual operations, as requirements may vary slightly under different working conditions.

He just has to do it in accordance with the national standards

I. Key requirements of TSG 31-2025 for retesting the mechanical properties of foreign-grade materials. Preliminary review requirements: It is necessary to first examine the quality certification documents of such foreign-grade materials to confirm that they are compliant materials permitted under the current standards for pressure pipelines abroad and for which there are examples of use in similar operating conditions; their chemical composition should be comparable to that of similar domestic materials, and their performance must meet or exceed the basic requirements specified in TSG 31-2025 before retesting can proceed. Mandatory performance requirements: The retesting must meet the strict criteria specified in TSG 31-2025: the elongation after fracture for castings and non-ferrous metals must be ≥14%, while for steel materials (excluding bolts) it must be ≥16%. The materials must also possess sufficient resistance to brittle fracture at the lowest operating temperature. II. Specific methods for re-inspection: Sampling rules: Samples shall be taken from pieces with the same furnace number, batch number, and specifications. For impact tests, 3 Charpy V-notch specimens are taken per group; for specimens with a thickness of ≤50 mm, sampling is done at the center, while for those with a thickness >50 mm, sampling is done at the 1/4 thickness position. Test items: Tensile testing under cover (to determine tensile strength, yield strength, and elongation after fracture), Charpy V-notch low-temperature impact test; additional mechanical property tests such as cold bending may be conducted if necessary. Result evaluation: All values obtained from retesting must meet the corresponding standard requirements; the results are included in the product quality certification documents to create a complete and traceable quality record. III. Execution standards for re-inspection criteria: Domestic basic general standards – It is necessary to meet the requirements of TSG 31-2025 \"Safety Technical Regulations for Industrial Pipelines\", GB/T 20801, and GB/T 32270 simultaneously. The impact tests shall be conducted in accordance with GB/T 229 \"Metallic Materials – Charpy Pendulum Impact Test Method\". The determination of results and the rounding of values for steel re-inspections can be carried out in line with the rules specified in GB/T 1591.1. Correspondence between foreign brand names and original manufacturer standards: It is necessary to comply simultaneously with the standards of the country of origin associated with that foreign brand name. For example, materials that meet American standards must adhere to the corresponding ASTM/ASME standards (such as SA-516/SA-516M), while materials that meet European standards must follow the corresponding EN/DIN standards (such as EN 10028-3), to ensure that the retesting requirements are in line with the technical specifications of the materials as originally specified. Additional requirements for domestic manufacturing: For materials of foreign brand names that are manufactured by domestic entities, they must also meet the testing methods and inspection rules specified in the specific corporate standards established by those entities for that particular brand name.