I once had to weld a hole in my car gas tank .So i took the tank out and filled
it with water I emptyed it and did this 3 times . But i still smelled a slight
gas smell .So i rolled up a news paper about 3 foot long put one end in the
tank and lighted the other end and got away from it.To my suprise there was a
loud bang .It expanded the tank alittle but a mashed it back in and fixed the
hole.