Abstract: Employee #1 was replacing armrests on Catapillar bulldozers using a cutting torch to remove bolts. Prior to incident, Employee #1 had completed a similar assignment on another bulldozer using same method to remove old bolts. In this instance, the battery which had no cover, was located on left outer side 18 inches beneath the armrest. Employee #1 had cut the first bolt and had just started to cut the second bolt when hot slag sparks landed onto the battery, causing the plastic case to melt and gas forming from the heat exploded. Employee #1 sustained first degree burns to his face from the fire ball created by the fire and explosion. Fire immediately went out after the explosion. The weather was overcast with light misty rainfall. Employee #1 did not remove combustible and flammable items from the work area, such as the battery, or attempt to cover the battery during hot work of cutting with an acetylene and oxygen torch. Employee #1 did not use welder's or other type of eyeglasses during the cutting operation.