I think the trick when welding/cutting on drums/gas tanks is to remove the air. Without oxygen, no boom.....hence electric fuel pumps in your car's gas tank....plenty of gas fumes in there, but no oxygen to support combustion.
I've seen the water trick, and the exhaust hose version Dwight speaks of, both methods displace the air in the tank, preventing an explosion. Hopefully.
Ever see those guys who put cigarettes out in buckets of gasoline? I understand how they're able to get away with it, but I still don't like to be around when they're showing off.
