A worker was using an Oxygen/Acetylene torch setup on a cart, a portable welder, and a grinder. Apparently the Acetylene hose developed a leak and ignited during the grinding operation. A worker attempted to extinguish the blaze with a nearby fire extinguisher however he quickly determined that the fire was beyond his capabilities. The area was evacuated and the fire department was immediately dispatched to put out the fire. There were NO injuries.