The welder qualified to weld open root joints, i.e., 6GR, can weld the root bead and perhaps the second layer. A welder qualified with backing can then weld the remainder of the joint provided the thickness limitations isn't exceeded and the 24 inch diameter restriction is observed.
Remember, a performance test on plate has a restriction on the minimum diameter that can be welded.
Best regards - Al
While one could argue the fact that it is always and completely a CJP, that won't be an issue seeing as how the diameter won't qualify. Doesn't matter how many different tables the issues is confused by it still stands that the plate qualified welder can only weld tubular 24" and above.
Have a Great Day, Brent