[Captainfab]

Thanks for posting that Ron. I have used exhaust gas to purge 3 old gasoline storage tank (several thousand gallons) I was welding on, and had no issues. A few years later I learned of the dry ice trick. I think that's what I would use if the situation arises again. On diesel tanks I don't worry much, just drain them as good as possible, leave the cap off and open up every port possible, so it can vent. It's the gasoline tanks that scare the crap outta me.