We have a WPS and PQR for welding 316SS to 316SS. Can the WPS for 316SS also be used for 321SS and 347SS. We would be welding the same product - just different grade of material.
The PQR can be used to support welding all three alloys. Generally, you should match the filler metal chemistry to the materials being welded. This can be done by amending your WPS appropriately or creating a new WPS suported by the original PQR.