Not sure of the depth of your question, but overall (if I am understanding you correctly), yes.  A welder qualified to a pipe test per Clause 9 will be qualified to certain aspects of plate. 

Qualify to a 5G for pipe and you are good for most positions of plate welding.  Qualify for 6G and you will be qualified for all position plate.  The one point you will have to be mindful of is thickness.  For unlimited thickness you must use the heavy/monster coupons to get enough wall thickness. 

Similar to, if qualified in all position plate, you are qualified for some pipe applications.  Pipe 24" or greater in diameter is allowed with a plate qualification. 

Have a Great Day,  Brent