Application of Reliability Techniques to Evaluate Maintainability of Centrifugal Pump used for Petroleum Product Delivery

Proper Maintenance can be the major factor in distinguishing between a reliable pump and one which breaks down often. In this study, data concerning component life and occurrence of problems in centrifugal pumps was collected from a downstream petroleum product depot. This study analysed 40 occurrences of failures on 5 pumps used for 3 different products: PMS, AGO and DPK. Of these failures, mechanical seal occurred 13 times, suction strainer and coupling rubber occurred 6 times each, and other components accounted for the remaining. Mean Time Between Failures were computed as 1600hr, 1600hr, 4800hr, 738hr, 9600hr, 4800hr, 9600hr, 2400hr and 1920hr for Coupling Rubber, Suction Strainer, Pump Bearing, Mechanical Seal, Electrical Motor, Pump Casing, Oil Seal, Motor Coupling and Impeller respectively. Failure rates (λ) were computed as 0.0625%, 0.0625%, 0.0208333%, 0.1354167%, 0.0104167%, 0.0208333%, 0.0104167%, 0.0416667%, 0.000520833% and 0.0416667% in the same order. Ishikawa diagrams were used to present Root Cause Analysis of failures. Failure Modes Effects and Criticality Analysis was employed to analyse data. Cost analysis was done on current maintenance plan and a cost-effective and optimal Maintenance Plan was recommended for every Centrifugal Pump user. The idea behind this plan is to replace the maintenance work on mechanical seal and suction strainer from time-based to condition based. The new plan was shown to reduce total costs by 40% without compromising availability of equipment. With adherence to this plan, users can easily be rest assured of a pump with high reliability, available for use 97 percent of the time.