Sadra,
The omission but not addition of backing or backgouging is an essential variable as per point 35, table 4.5. So if you are not changing groove design but only employing backwelding in a single Vee for eg, when the PQR is qualified single Vee single sided welding, no requalification is required.
Gerald
I have faced a lot of problems in convincing clients on your point. I agree that a change in groove type is essential only if joint detail does not meet the requirements of one of the prequalified joint details in section 3 of D1.1. In addition for a given joint design, the tolerances for root, face and groove angle should meet the tolerances spelt out in 3.12,3.13, 3.13.4,5.22.4.1 and 5.22.4.2. Thanks and regards
Sayee Prasad R
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