that true Dave and the real problem comes when the tank gets very hot and the fuel starts to boil - there will/should be a venting process to prevent a breach if its not cooled the next stage is a Bleve (pronounced Blevvy) boiling liquid expanding vapour explosion at which point you really want to be several miles away preferably in somewhere very solid say a nuclear bunker? theres a movie of a small road tanker having a bleve at