Study On Maintainability Of Large Water Pump Units

Large pump unites demand of high reliability and economy; especially the East Route Project of South to North Water Transfer (ERP), which is long running time, short maintenance time and heavy maintenance working. If failures of a pump unit in some step pump station occurs, or the pump unit is not checked and repaired timely, quickly and accurately, or the pumping discharge can not be guaranteed, it will influence the operation of other step pump stations, even the whole water transfer project. Therefore, the pump unit reliability is considered primarily, and maintainability is one of the most important aspects of reliability. The maintainability of large pump stations is related with whether operating functions are drought-resistant, draining waterlogged, transferring water for large pump stations, and guaranteed and displayed long, stably or not. Main works in this dissertation are as follows:Common failures of pump unit were investigated, reasons of failures were analyzed, and inspection procedures of eliminating parts failures were simply described. According to related theories of maintainability, aiming at the characteristics of pump unit failures, influencing factors of unit maintainability were analyzed. Qualitative and quantitative indicators were put forward to evaluate large pump units'maintainability. Practical models were established to evaluate the maintainability of pump units'key parts, and the maintainability of common and key parts- guiding bearings of water pump was evaluated. Maintenance synthetic methods of multi-maintenance process with uncertainty were put forward. Evaluating models of pump unit maintenance was established based on reliability. The maintainability of typical pump units was calculated, compared and analyzed. Synthesizing multi-aspect factors, measures to increase pump unit maintainability were presented.The results show that main failures are that a thrust bearing liner of motors is burned, failures of stator and rotor coil insulation of motors, guiding bearing and shaft neck of pumps are abraded, pump cavitations, adjusting mechanism of blades fail etc. Main factors of influencing pump units maintenance time are that related characteristic numbers of pump units, key parts structures, maintenance resources and synthesis disposition of persons etc. Main factors of influencing pump units maintenance costs are that failure rate, maintenance cycle, cost of labor used, changing costly parts etc. Pump units and guiding-bearing structure patterns influence guiding-maintainability, the maintainability of water lubricate guide bearing is better than that of the oil-lubricate bearing. As for oil-lubricate bearings maintainability, a vertical pump is better than a bulb tubular pump. Pump units structure pattern,size and key parts structure pattern are main influencing factors in pump units maintainability. The pump unit's structure pattern influences equality of metal elbow casing pump units and half-well casing pump units. Horizontal pump unit is disassembled and installed heavily, but it is a little time to adjusting installation elements, the total maintenance time of it is less than that of vertical pump units of the same size.Through many measures which maintainability elements are improved, specially the improvement of structure patterns of pump units and key parts, the choosing of proper maintenance measures, the adoption of the current maintenance mode and the establishment of reasonable maintenance system improve the maintainability of large pump units.