I welded mine with a Lincoln Weldpac 100. I have the MIG kit (see Adventures in welding stainless thread). I used a 308 alloy and a flux that is the equivalent of Solar mixed with denatured alcohol per the instructions. Watch BobbyM's youtube on welding on keggles. Even though he TIGs, you can see how to flux your weld. Also, he makes some great comments on cleaning the coupling and the area around the weld. I used the tri-mix gas. The hole for the coupling needs to be very tight. The coupling is much thicker than the keg so you need to carry the heat on the coupling and "whip" it down to the keg. Also, keep your machine hot and move quickly. Only weld about 1/2" at a time. Move 1/2 way around the coupling to stitch weld. Brush the weld area each time you pause to let the metal cool. Once you have gone around the coupling, take a "stainless only" (one that has not been used on carbon steel) grinding disk and grind just the weld. DO NOT get into the keg, it's thin enough already. Any "holes" or "holidays" you see in the grinded metal need to be filled in. Make sure you clean and re-flux the back side each time. If you burn through, turn your machine way down and weld up the holes. If you cant "catch" a crack, move ahead of it about 1/2" and make a weld. That will help stop the run. Ditto on the re-fluxing. Make sure you reach inside the keg and grind/polish the places you burned through. Look at the backside after you weld it. there should be a black ring all the way around the coupling. Use a mirror to make sure the ring goes all the way around. If you don't see a solid ring, it's going to leak. Check it for leaks. If it doesn't leak, use one of those "flap disks", not a grinding wheel to polish the weld area. Then, check it for leaks again. Finally after you finish, and the metal cools down, scrub it with Bar Keepers Friend and let it set a couple of days to "re-pickle" the stainless. I only did it because I was hard headed and wanted to prove to myself that I could. It would have been ALOT less frustrating to have it professionally done. the weld kept cracking and I had HELL getting it sealed. I definately would not try it on the "cold" side. Well, that's probably not true, but it would look like hell. I'll probably post some photos of my build, especially the welds so we can all have a bench mark for UGLY welds. Let us know what you decide and how it turns out. Luck - Dwain