I am wondering why there is a difference between the requirement for the procedure qualification tests as listed in the structural Codes AWS D1.1 vs AWS D1.6?
Specifically, D1.6 does not seem to make UT/RT inspection a requirement for PQR qualification where D1.1 does.

ccasey-
I don't know why there is that difference. Each committee has their own reasons for their requirements. You would have to sit on a committee or possibly talk with one of the AWS engineers to see if they knew the specific reason for the UT/RT requirements in one and not the other,
It is very typical to see such variations in each code or specification and that is the very reason that if a code/specification is called out on the contract then all people involved with the welding need to know the specifics of the code/specification that applies to the weldments used.
Wish I had more of an answer--but be glad as it saves you the extra expense of the RT/UT on the plates.

Ken K