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Welding procedure qualification is a verification test of welding procedures carried out under the specific conditions of the manufacturing unit, based on tests of the welding properties of steel materials and taking into account the structural characteristics and technical requirements of pressure-bearing special equipment. Its purpose is to assess whether the welding procedure manuals developed by the welding contractor are appropriate, and whether the contractor has the capability to produce weld joints that meet safety regulations and product technical requirements. Definition: Welding procedure qualification is a testing process carried out to verify the correctness of the welding procedure for weldments, as well as an evaluation of the results. Characteristics: Welding procedure qualification addresses the welding procedure issues related to steel under specific conditions, rather than determining the optimal process parameters. The evaluation process is based on the welding properties of the raw materials, with production guided by technical condition tests. Purpose: To assess whether the welding contractor has the capability to produce weld joints that meet the requirements of relevant ** or industry standards and technical specifications. Verify whether the welding procedure specification (WPS or pWPS) prepared by the welding contractor is correct. To provide a reliable technical basis for developing formal welding procedure specifications or welding process cards. Significance: Welding procedure qualification is an important measure to ensure welding quality, as it enables the verification of the correctness and rationality of the welding procedure specifications prepared for various welded joints. Through welding procedure qualification, it is possible to verify whether the performance of the welded joints fabricated according to the established welding procedure specifications meets the design requirements. To provide a reliable basis for formally establishing welding procedure specifications or welding process cards. 5. Common evaluation criteria: These include domestic standards such as NB/T 47014 \"Welding procedure qualification for pressure equipment\" and GB 50236 \"Construction of field equipment and industrial pipeline welding projects sowie welding procedure qualification for pressure pipelines\", as well as international standards such as the European standard EN 288 or the ISO 15607–ISO 15614 series of standards. American standards such as AWS D1.1/D1.1M \"Welding procedures for steel structures\" are also applicable; the latest versions of these standards shall be followed. Taking a typical welding procedure as an example, the process is as follows. (1) Welding procedure qualification shall be carried out after the preparation of the welding procedure specification and before the production of welded products. The process is as follows: l) Prepare the welding procedure specification. 2) The test pieces are welded by skilled welders from this unit in accordance with the welding procedure manual. 3) Perform visual inspection and non-destructive testing on the welded joints of the test specimens. 4) Specimens for mechanical property tests, including tensile, bending, and impact specimens, were cut from the above-mentioned test pieces that passed the inspections. 5) Determine whether the sample possesses the required mechanical properties. 6) Submit a welding procedure qualification report. (2) Welded joints that require a welding procedure qualification include: 1) Welded joints of pressure components. 2) Welding die head welded to the compressed element. 3) The tack welds of the aforementioned welds. 4) Weld overlays and repairs on the surface of the base material of the compressed components. The above includes various types of joints such as butt joints, corner joints, and composite joints.