Operators in a powdered metals production facility heard a hissing noise near one of the plant furnaces and determined that it was a gas leak in the trench below the furnaces. The trench carried hydrogen, nitrogen, and cooling water runoff pipes as well as a vent pipe for the furnaces.

Maintenance personnel presumed that the leak was nonflammable nitrogen because there had recently been a nitrogen piping leak elsewhere in the plant. Using the plant's overhead crane, they removed some of the heavy trench covers. They determined that the leak was in an area that the crane could not reach, so they brought in a forklift with a chain to remove the trench covers in that area.

Eyewitnesses stated that as the first trench cover was wrenched from its position by the forklift view more

A battery that was left on a charger over a given weekend was used to start a gasoline power generator. This battery was connected in series with another battery and the connection on the negative post was hand tightened. When an attempt was made to start the generator, the battery exploded on approximately the fifth click of the starter solenoid. No damage was done to any equipment or facilities and no one was injured.

The most probable cause of the accident was the severe overcharging of the battery (64 hours at 20 amp/hour). This charging created hydrogen, which combined with air or oxygen and an ignition source to form the explosion. One source of ignition could have been the loosely attached connection to the battery terminal. Another possible source may have been an view more