I had a drum to cut the top off of. Had a "little" powder in it that smelled like peppermint, put a little water in the drum with only a peak of 1" or 2" diameter sticking out of the water. Started cutting with arc welder and when almost done with only 2-3" to go I heard a whistle and lifted up My hood. A stream of sparkler type flames was coming out of the big hole in the lid. A couple of seconds after I lifted My hood a fireball about 6" in diameter came out and went up 2 or 3' with a big poof. No harm, no foul, next time the barrel will be filled to the top. The slag must have evaporated enough water to make it less than safe. Had a boss who asked a worker to cut a drum open and it took off His head.