We have qualfified SAW welding 2G acc to joint B-U5B (Clause 4), however, joint B-U5B is not for SAW. I Know that SAW is in general not Qualified on SAW.
Since you a using SAW, why not eliminate the spacer and use B-U3c-S? I don't know your material thickness, but with SAW a one sided weld would be more efficient, B-U4b.