Travelover
Elite Member
I bet you washed it, but didn't really flush it, which means filling it completely with water, to displace both any remaining gas, and any vapor in the tank.
It was full of water when it blew. All I can figure is that there was a residual amount of gas in the crevices that was forced out by the heat of the torch. In any case, that was the last tank I'll ever apply flame to.