Failure Analysis of the Shaft and Impeller of Centrifugal Lubricant Pump
Abstract
This paper studies the failure of the shaft and impeller of a centrifugal lubricant pump, including analysis of the failure process, the reasons for the failure, inspection and judgment of the failed parts, and the replacement of the failed parts. The purpose of the analysis was to understand the failure process and provide scientific maintenance guidance for similar failures. The result shows that the damage of the impeller is mainly related to the large number of electromagnetic particles injected from the bearing of the pump shaft during use, usually caused by the exposure of the sealing ring to the outer environment. In order to improve the service life of the pump shaft and impeller parts, the maintenance personnel should pay more attention to the selection of lubricants and seals during use, replace parts in a timely manner, and do regular maintenance work.
Introduction
Centrifugal lubricant pump is a large-capacity centrifugal pump with strong power, which is widely used in chemical, metallurgical and gas transmission in the lubrication of high temperature, large flow and low pressure system. Due to the continuous operation of the centrifugal lubricant pump, the bearing of the pump shaft is easily worn, the sealing ring is damaged, and the quality of the lubricating oil will decrease after a period of operation, resulting in damage to the impeller. Therefore, it is necessary to analyze the failure of the shaft and impeller of the centrifugal lubricant pump and make corresponding maintenance and replacement.
Analysis of Failure Process
The failure process of the centrifugal lubricant pump is usually divided into three stages: the initial stage, the serious stage and the total destruction stage. In the initial stage, the bearing at the pump shaft is slightly worn, which will lead to the decrease of the pump outlet pressure and the change of the working current. In general, the lubricating oil used in the bearing will appear dark abnormal and abnormal bubbles. In the serious stage, the impeller will start to deform and cause damage due to the decrease of the inlet pressure. At this stage, the impeller will be machined, polished and welded. In the total destruction stage, the shaft of the centrifugal lubricant pump will break and must be replaced immediately.
Analysis of Reasons for Failure
In general, the reasons for the failure of the shaft and impeller of the centrifugal lubricant pump are mainly due to the increase of foreign particles, the grind rate of the lubricating oil, the wear and tear of the components of the pump, the increase of temperature and vibration and the poor sealing performance of the parts.
Inspection and Judgment of Failed Parts
It is necessary to inspect and judge the failed parts of the centrifugal lubricant pump before replacement. The inspection method is usually visual inspection or caliper measurement. The components can be inspected and judged according to the drawings. If the parts have obvious losses, severe scratches and serious deformation, it is necessary to replace the parts.
Replacement of Failed Parts
The replacement of the failed parts of the centrifugal lubricant pump should refer to the relevant maintenance manuals. Generally speaking, the impeller should be removed from the pump shell before being replaced. After disassembling, the worn parts and wear marks should be inspected and measured, and then, new parts with the same specifications should be installed after inspection. After assembling, it is necessary to test the pressure and temperature of the impeller as required to confirm whether the installation is qualified.
Conclusion
In this paper, the failure process of the shaft and impeller of the centrifugal lubricant pump is analyzed in detail. The reasons for the failure are mainly related to the increase of foreign particles, the decrease of the grind rate of the lubricating oil, the wear and tear of the components of the pump and the poor sealing performance of the parts. At the same time, it is necessary to pay attention to the selection of lubricants, seals and parts when replacing the failed parts. Regular maintenance work should be carried out to ensure the normal operation of the pump and prolong its service life.
