Dear Friends
I'm not familiar with ASME Codes
Detail of qualified 6G Welder:-
Weld Process - GTAW 
base material  P or S No- S8(Spec.-A312/Grade-TP316L) / Thk 6.0mm x 2.0": Dia
Filler Metal Spec - SFA 5.9 / Classification - ER316L - F No - F6

Query in ref to QW-423.1
1) What is his qualification range and limitation?
2) Am i right to say that he is qualified to  WELD base materials ranging from - P or S No 1 to 11(inclusive of 10H ,10J & 10K?), 34 , 41 to 49?
3) Any restriction in welding super duplex SS materials?

Thanks