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 execution of 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. This part of ISO 15614 applies to all welding processes suitable for overlay welding. In situations where qualification is carried out on a pre-production test piece, the qualification is performed in accordance with ISO 15613 except that, as far as possible, the testing is according to this part of ISO 15614. Building up and repair of parent metal is covered by ISO 15613 or ISO 15614-1. This edition of ISO 15614-7 is applicable to all new welding procedure qualification tests. It does not invalidate previous welding procedure tests made in accordance with previous editions of this part of ISO 15614. Where additional tests are required by the present edition, it is only necessary that those additional tests be carried out on a test piece made in accordance with the existing WPS and this part of ISO 15614. If buttering is used for welding between dissimilar materials, the welding procedure is qualified in accordance with ISO 15614-1. This buttering may be required for weld combining different material structure or properties, e.g. joining martensitic steels or ferritic steels with austenitic steels. Additional tests may be required by application standards.