Hi Doug,
I thought the whole intent was to get around qualifying a procedure, and using the prequalifieds would have accomplished this, but 4.12.2 specifically says the CJP Butt joint welded from one side without backing ...WPS shall be qualified and to use Figure 4.24 for that joint without backing and welded from one side.
Anyway, I may have gotten side tracked on the original question with my assumptions, if I did, sorry for the confusion.
John Wright
edit... I'm all wet, this is all listed under Tubular Connections.(4.12)