This part of ISO 15614 specifies tests for the qualification of welding procedure specifications applicable to upset (resistance butt) welding and flash welding of metallic materials, e.g. with solid, tubular, flat or circular cross-section. Its basic principles can also be applied to other resistance welding processes when this is stated in the specification. This part of ISO 15614 defines the conditions for carrying out tests and the limits of validity of a qualified welding procedure for all the practical welding operations that it covers. The tests required to qualify the procedure for a particular component or assembly depend on the performance and quality requirements of the component or assembly, as defined in the design specification. The tests are intended to be carried out in accordance with the requirements of this part of ISO 15614, unless more severe tests are specified by the relevant application standard or specification and when these apply. NOTE Specific service, material, or manufacturing conditions can require more comprehensive testing than specified by this part of ISO 15614. Such tests can include microsections, fatigue or endurance tests, impact tests, radiographic testing, ultrasonic testing, corrosion testing and tests of components or complete welded assemblies. This part of ISO 15614 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 upset welding, using direct current or alternating current with various pressure sequences.