side water branch stud extraction

[Chris KC]

I should have thought a plug weld would work a treat, as long as the sheet/ bar it is welded through will take the torque of untightening.
My worry would be that the flange will break before the 'studlet' comes out. Or that the heat might do a mischief to the cast block.

Can you not simply grind flush and re-drill & tap? If accurately centred (admittedly challenging) you might get lucky and end up with a clean result; failing that drill and tap oversize?

edit: I see I have crossed wires with Robert - looks like we're on the same page though.