There are 2 thickness involved, Base metal (BM)Thickness and Weld metal (WM)thickness. Yes, you can prepare a separate WPS for GTAW from the PQR.
When Impact test is Applicable.
BM thickness Qualified, minimum is 10.97mm so you cannot prepare a GTAW WPS.
When Impact test is not Applicable
BM thickness Qualified, 5mm to 7.0mm (though maximum is 21.94mm)
WM thickness Qualified is maximum 7mm
Thanks & Regards
J.Gerald Jayakumar