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Old 11-01-2016, 12:22 AM
Princhester Princhester is offline
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Join Date: Jan 2001
Location: Brisbane, Australia
Posts: 14,257
Originally Posted by Francis Vaughan View Post
Working on an actual fuel tank is potentially dangerous. Then again a friend of mine worked at a service station when he was a kid, and remembers how one mechanic was very careful when a fuel tank needed repair. He removed the tank, drained it, rinsed it twice with water, and then took to it with a welder. It exploded violently. Didn't kill him, but it wasn't good. Other old hands claimed the safest thing to do was to leave the tank half full of fuel.
His mistake was to drain it and rinse it; this would have left just enough fuel in the tank to provide enough vapour to form a nice explosive mixture.

My grandfather ran a mechanical engineering workshop in a rural area and he refused to do hotwork on fuel tanks which cost him business. Most workshops would fill tank with water, to overflowing, before welding on them. This is very safe unless - as has happened more than once - there is a little bit of fuel vapour trapped in a folded seam of the tank. It is of course the seams which tend to require re-welding.