This document specifies how a preliminary welding procedure specification is qualified by welding procedure tests. This document defines the conditions for the execution of welding procedure tests and the range of qualification for welding procedures for all welding operations within the qualification of this document. The primary purpose of welding procedure qualification is to demonstrate that the joining process proposed for construction is capable of producing joints having the required mechanical properties for the intended application. Two classes of welding procedure tests are given in order to permit application to a wide range of welded fabrication. They are designated by classes A and B. In class A, the extent of testing is greater and the ranges of qualification are more restrictive than in class B. Procedure tests carried out to class A automatically qualify for class B requirements, but not vice-versa. When no class is specified in a contract or application standard, all the requirements of class A apply. NOTE Class B corresponds to Level 1 and Class A corresponds to Level 2 according ISO 15614-1. This document applies to upset (resistance butt) welding and flash welding of any metallic materials in all product forms (e.g. with solid, tubular, flat or circular cross-section). It covers the following resistance welding processes, as defined in ISO 4063: 24 flash welding, using direct current or alternating current with various movement sequences, constant flashing and pulsed flashing; 25 resistance butt welding (upset welding), using direct current or alternating current with various current- and pressure sequences.