Dear experts,
I'm writing WPS for overlay following ASME IX, but I have a concern about section QW 403.20 " If the chemical composition of the weld metal overlay is specified in the WPS, a change in the P-Number listed in Table QW/QB-422 to another P-Number or unlisted base metal, or a change in Group Number for P-No. 10 or P-No. 11 base metals.
If the chemical composition of the weld metal overlay is not specified in the WPS, qualification on P-No. 5A or any lower P-Number base metal also qualifies for weld metal overlay on all lower P-Number base metals".
I hope that you can help me to explain about this paragraph. If possible, please give me a specifc example. Thank you all!