Quote:
Originally Posted by brndck
back purging (filling the internal cavity of the manifold with inert gas, usually argon) is not the same as what he's asking.
some mfrs will weld the inside of the flange areas as well, not just weld beads around the outside.
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I?m aware of what back purging is. Back purging and having enough heat penetration creates what appears to be a weld on the inside. If you do not back purge, you end up with sugary welds and blobs on the inside of the piece you?re welding on. There is no physical way to get your Tig torch into the inside of a piece of pipe and weld it, let alone blindly.