Can I raise the min. thickness of base metal qualified in ASME IX

[engr2GW]

Although ASME IX gives min. and max. thickness range of base metal qualified by a size of coupon, can I raise the thickness min. if I want, I know I can lower the max for some reasons like PWHT, etc
e.g 1/16" to 2T, can I say 0.154" to 2T instead for the application I want to use it for/
Thanks a lot.

 

[weldtek]

You can certainly tighten up the ranges for variables from that allowed by Code.
For example, some of our customers impose thickness restrictions for certain materials such as duplex stainless steels, far in excess of Code rules. Those kind of changes don't invalidate a WPS.

 

[Mr168]

Your PQR's only establish your minimum and maximum permissible ranges. Your WPS can state whatever you'd like it to within said ranges, though typically you'd want to ensure that they also satisfy the intended code of construction on "open" variables such as PWHT temperatures/duration.