Explosion !

October 2009. Jahn is in his room working on the computer.

Suddenly he is hearing the sound of a huge explosion from the garage area. "Has Dad killed himself he thinks?" and goes to investigate.

The outside garage light glass is on the ground in bits. Inside the garage there is smoke, and on the floor is a lump of mangled metal and small bits of gasket material burning. A wood chisel is embedded in the ceiling isolation; the vacuum cleaner pipe running along the ceiling is broken to bits. Dad is standing next to the mess with a burning oxy torch in his hand, grinning. 

 'It exploded' he explains. (Stating the obvious). 'I was going to weld the drain cock to the bottom of the tank when it happened.' 

He has spent many weekends making the tank for his historic car; the only thing left to do was the drain cock. So he cleaned the area around the drain hole with a chisel, ready for welding and left the chisel on top of the tank.  As soon as the torch came close to the drain hole, the tank exploded, blew its sides out, shot the chisel into the ceiling insulation and then the tank itself up to the ceiling, breaking the vacuum cleaner pipe before landing on the floor in a heap.

There has never been any fuel in the tank, so suggestion is some thinner must have remained from the painting job. No damage to anything else, Dad included. He is salvaging what he can to make another tank.

Comment and Recommendations from Tony Atkinson

I wonder what he was using to 'weld' the tank's drain cock in with!  The tank material was gal steel sheet (no paint/thinners).  He say's in the story that "Dad is standing next to the mess with a burning oxy torch in his hand" so I figure that the tank must have got some Acetylene in it prior to lighting the torch as Acetylene has an ignition range of between 2% & 98% air-mix. For comparison, LP Gas has an ignition band of between 9% & 18% which means that below 9% it is too lean to burn & above 18% it is too rich.

Any tank should be purged of all gases prior to going near them with a naked flame & this can simply & cheaply be done by filling the tank to the brim with water!  Also, a tank could be purged by running a pipe of some kind from the exhaust of a car so as to fill the tank with CO fumes - not really recommended for confined places like a closed garage though.