Piece-part reliability-allocation using actual failure data

The author documents the piece part failure assessment and predominant failure mode analyses performed on the US Strategic Petroleum Reserve (SPR) sites to provide piece part failure rates for the various classes of equipment. These data would then be used in a stock-level-allocation-model to determine the number of spares that should be stocked to meet particular mission requirements such as stock-out-protection-level. The analyses were performed using historical data extracted from failure reports and work orders obtained from the various SPR sites dating from January 1, 1984 to June 1, 1988. The analyses revealed that the predominant failure modes are wearout and part failure. Among pumps, the predominant failed parts were seals and bearings. Predominant failed parts among valves were difficult to determine, since the valves were usually replaced and failed components sent to the vendor for repair. For electrical equipment, the predominant failed parts were switches, fuses, and wiring. The predominance of reports of wearout and part failure as the major failure cause indicates that more frequent inspections and preventive maintenance are required