Well, that's always a good sign! Tool-time Tim notwithstanding, there's nothing funny about blowing ones-self up. By the way, welding a gas tank is a piece of cake if you fill it with water first. I've run an exhaust pipe into them and filled 'em with (theoretically) burnt gasses, but not all engines are terribly efficient and you still get the odd pop. No real damage, but hard on the nerves.