An incident due to the ignition of a fire at the top of an oil console of air and refrigeration compressors caused the shut down of an ammonia plant for five days. The cause: failure of refrigeration compressor seals resulted in the lowering of the oil level in the console. This caused cavitation in the oil pump suction resulting in high vibration in the pump discharge piping which led to the snapping of a 3/4 " diameter interconnection line weld joint. Oil splashing from the snapped joint to the nearby steam header with improper insulation caused a serious fire above the oil console.