Well I was asking about purging for stainless and what do you know, I run into a stainless job. I had a pool railing that was 1.90" OD and wall .065". It fits into 2 pockets in the pool and over the years the wedges that hold it in, and people yanking on it had dented in the side where the wedges fit. My job was to get the dents out [no time to order new rail] So... I drove an exhaust pipe expander in each end and pushed the dents out, worked good except I couldnt expand it enough to get the expander out...It had to fit back in the pockets at the pool..So I split the tube and pulled it out. I welded up both slpits and it seemed OK, looked inside and it didnt look to funny. Each weld was only about 6 inchs long and seemed to weld nice. I didn't back purge it, of course you cant see it, it's in the concrete. But it didn't weld funny either, looked nice on the outside. Tightened up real nice and looked good. I only have One large bottle of Argon, what arrangements do you use to back purge from the same bottle. Or do you use a different bottle?