Quote:
Originally Posted by marine02ss
What do u all mean by back gas?
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What that means is to purge the inside of the tubing with the shielding gas. Small temporary plugs on each end with a hose from the gas bottle will work. If you pressurize the inside of the tube you can blow the weld puddle outwards. You are only looking to create a protective atmosphere on the inside of the tube, the same protective atmosphere at the end of the torch created by the nozzle & shielding gas. Make two plugs, feed the gas into a plug on one end of the tube, and leave a small hole in the temporary plug on the other end of the tube so you do not pressurize the tube. Wood works, cardboard works, you can even use rubber bands and aluminum foil as the plugs and then just poke one hole for the hose and another hole on the other end to vent. Nothing fancy required.
The backpurging produces a cleaner weld on the inside surface.