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Scope of application 1. Welds applicable to (1) Welds of pressure-bearing components； (2) Welds welded to the compressed components ； (3) Positioning welds for the aforementioned welds: (4) Surfacing and repair welding on the surface of the base material of compressive components. 2. Applicable welding methods: Oxy-fuel welding (OFW), Shielded Metal Arc Welding (SMAW), Submerged Arc Welding (SAW), Gas Metal Arc Welding (including Flux-Cored Arc Welding) (GMAW, FCAW), Tungsten Inert Gas Welding (GTAW), Plasma Arc Welding (PAW), Electro-Gas Welding (EGW), Electroslag Welding (ESW), Stud Arc Welding (SW), Friction Welding (FRW), and other welding methods. Feature (1) is to address the welding process issues related to the materials used in pressure vessels under specific conditions, rather than to select the optimal process parameters; therefore, the welding process parameters chosen through welding procedure qualification fall within a certain range. (2) It addresses performance issues under specific processing conditions, but it cannot solve problems related to the overall quality of the equipment, such as stress elimination, reduction of deformation, and prevention of welding defects. (3) It is based on the weldability of the material, and production is guided through welding procedure qualification tests, avoiding the drawback of using actual products as test pieces; therefore, neither welding procedure qualification nor additional welding procedure qualifications are simulation tests or witness tests. (4) Human factors should be excluded, and weld process qualification should not be combined with welder skill assessment. The personnel responsible for conducting welding process evaluations should be able to determine whether the causes of defects and deficiencies are related to welding process issues or the welder’s skills; if it is a skill issue, it should be resolved through welder training. (5) For the inspection items of welding procedure qualification specimens, it is required to test only the mechanical properties (tensile strength, impact resistance), bending properties, or the chemical composition of the surfacing layer. The standard \"Welding Procedure Qualification for Pressure Equipment\" does not apply to situations that fall outside the scope of the standard, or to changes or additions to the requirements for specimen testing. If it is required to add inspection items such as stress corrosion and intergranular corrosion of austenitic stainless steels, not only the corresponding inspection methods and judgment criteria must be provided, but also the scope of application for the welding process after it is deemed qualified. (6) Welding procedure qualification shall be carried out within the organization. The equipment and instruments used for welding procedure qualification must be in proper working condition; the metal materials and welding materials shall comply with relevant standards, and the welding of the test pieces for welding procedure qualification shall be carried out by skilled welders from the same organization, using the equipment available at that organization. (7) A qualified welding procedure refers to the important factors and additional factors among the general welding procedure qualification factors and specific welding procedure qualification factors listed in the qualified welding procedure qualification report. (8) For the welding procedure qualification of pressure vessels, in addition to complying with the standard for Welding Procedure Qualification of Pressure Equipment, it shall also meet the relevant standards and technical documents for pressure vessel products.