For applications where supplemental essential variables apply (impacting testing), the welding procedure would be limited to P1 Groups 2 and 3 materials.
For applications where supplemental essential variables do not apply, you could use the WPS for any P1 material.
Your WPS would need to clearly show this delineation.
if impact testing is required by the code of construction and QW-403.5 is applicable your above mentioned PQR P1G2-P1G3 qualifies for:
P1G2-P1G2
P1G2-P1G3
P1G3-P1G3
QW-403.5:
"......
For ferrous materials in Table QW/QB-422, a procedure qualification shall be made for each P‐Number Group Number combination of base metals, even though procedure qualification tests have been made for each of the two base metals welded to itself. If however, two or more qualification records have the same essential and supplementary essential variables, except that the base metals are assigned to different Group Numbers within the same P‐Number, then the combination of base metals is also qualified. In addition, when base metals of two different P‐Number Group Number combinations are qualified using a single test coupon, that coupon qualifies the welding of those two P‐Number Group Numbers to themselves as well as to each other using the variables qualified. ......"
Interpretation Number : IX-15-15
Background: A test coupon has been welded using SA-333 Gr. 6 (P-No.1 Group 1) to SA-350 Gr. LF2 (P-No.1 Group 2) resulting in an impact tested (weld and both heat-affected zones) Procedure Qualification Record.
Question: May a WPS be written, supported by this PQR using the variables qualified, for welding all P-No.1 Group 2 materials to themselves, e.g. API 5L X65?
Reply: Yes
Interpretation Number : IX-79-94
Question: Is it the intent of QW-403.5 to permit qualification of two different Group number materials within the same P-Number welded to themselves by welding one Group material to the other Group material and impact testing the heat affected zone on both sides of the weld and the weld metal?
Reply: Yes, provided the same essential variables, including electrodes of filler metals, are used when welding each base metal Group to itself.