This part of ISO 15614 specifies how a preliminary welding procedure specification for overlay welding is qualified by welding procedure tests. This part of ISO 15614 defines the conditions for carrying out welding procedure tests and the range of qualification for welding procedures for all practical welding operations within the range of variables listed in Clause 8. Additional tests may be required by application standards. This part of ISO 15614 applies to all welding processes suitable for overlay welding. This part of ISO 15614 is applicable to all new welding procedures. However, it does not invalidate previous welding procedure tests made to former national standards or specifications. Where additional tests are carried out to make the qualification technically equivalent, they are only done on a test piece made in accordance with this part of ISO 15614. This part of ISO 15614 does not apply to overlay welding where cracks are intentionally produced (e.g. special hardfacing applications).