Well in accordance with our State Boiler Inspector it has to be H-7 and B-2 per code. This was for the fasteners on the pressure operated relief valves. He also pointed out that the valves were remanufactured at the same plant as the original manufacture and that this was not an acceptable code...
Welding backing bars are an off the shelf item at most welding supply shops.
AWS D1.1 requires that the composition and size be detailed on the WPS. Good Luck!
Iven 8-)
