B31.1 para 127.4.1 (C) "Tack welds permitted to remain in the finished weld shall be made by a qualified welder."
B31.1 para 127.4.1 (C) "Tack welds made by an unqualified welder shall be removed."
Thanks for that js55.
With backing rings, I tell the welders that they are to proceed as if all of the tacks are bad unless they made the tacks. If it was open butt welds where they could examine the ID and OD that would not be my instruction. They grind most of the weld metal on the tack down and feather the start and stop to ensure that the tacker, if not the welder making the joint, did not leave any defects. Therefore I won't ever have to hear this excuse from the welder if a rejected RT on his weld occurs; "Must of been in the tack, I know my stuff was right."
Not that welders make excuses. I'm just saying...