Quote Originally Posted by Crusty View Post
I've heard a story about a welder called out to fix a crack in a leaking gasoline tank and supposedly the welder had the tank completely filled to the neck rim with gasoline, then set the top alight. While it was burning, he welded the crack closed since the flame atop was burning all the vapors away.

Ya really gotta trust your physics to do this but back in past days people were more willing to try things in an effort to get the job done.
I've welded up cracks in diesel tanks on heavy equipment several times by keeping the level above the crack the hardest part is to burn a rod hot enough that ihe arc is not contaminated by the leaking fuel but not so hot as to burn a larger hole while you are welding.
Even more exciting is to weld on a nipple to the lower area in the end of a 10,000 gallon diesel tank. then use a torch to pierce a hole in it.
Did that once as well I should say twice first and last time at the same time. At a construction site a tank was delivered then filled with diesel the problem was the tank had been positioned reversed from how they needed it to use and there was no nipple and valve for them to hook up their pump all of the equipment operators were sitting on the tail gates of their pickups about 50 feet away drinking beer watching me weld on the nipple, after welding it on and threading on a gate valve, I put a 7" long #4 cutting tip in my torch when I lit it up and proceeded to poke it through the valve and nipple to begin cutting a hole I heard a dozen pickups start up and begin backing away. I chuckled to myself and thought P***y's as I pierced a hole and held the torch in there long enough to make the hole as large as possible diesel and flame flowed out the hole with a vengeance until I was able to close the valve then it was just a matter of allowing the fuel on the dirt to burn itself out.
there was a lot of rumbling inside the tank as the molten metal and the flame of the torch was blown inside but rumbling was all it did. When I finished and they could see that the tank was not going to explode they backed their trucks to where they had been. You wusses got any beer left I asked. Man you must have stones the size of king Kong's to blow a hole in the end of a tank with thousands of gallons of diesel. Naa that is why I get paid the big bucks to drive this welding rig around now whos got an extra beer.