Originally Posted by Dog House Brew
When welding you place the coupling through the wall of the keg. Then the welder covers the back side with argon gas. He does this with another line coming from a regulator on his argon tank. Some use a can to contain the gas around the fitting. I just use foil tape to create the pocket. If you have a decent welder, he will know what to do. If not find another welder.
The preferred method would be to weld the fittings flush to the inside of the vessel.
Check out Junkster's work.
He is not even a welder by trade, but that's what you should be shooting for.
I give him much credit for doing fantastic work.
link to the threadhttp://www.homebrewtalk.com/f51/how-...d-look-332934/