【Weekly Question】Improvements and prevention for bearing water damage in long-shaft submersible pumps

Regarding the issue of bearing damage caused by water ingress in long-shaft submersible pumps, the following improvement measures can be taken: 1. **Improve sealing performance**: Ensure that all seals meet standard quality requirements, and regularly inspect and replace worn-out sealing components. Choose corrosion-resistant and wear-resistant materials to extend the seal life. 2. **Add an air seal**: Install an air seal unit in the upper middle part of the shaft copper sleeve to prevent sewage from coming into contact with the bearings. An air seal can create an additional protective barrier to prevent moisture from penetrating. 3. **Install bearing protectors**: Consider adding protective devices around the bearings, such as bearing shields, which can physically prevent sewage from coming into contact with the bearings. 4. **Optimize the hydraulic design of the pump**: Improve the hydraulic structure of the pump to reduce swirls and turbulence inside it, thereby minimizing the impact on seals and wear. 5. **Use an external oil supply system**: If conditions permit, consider installing an external supply system for clean lubricating oil, which can continuously lubricate the bearings through external oil circuits, thereby reducing the workload on the bearings in harsh environments. 6. **Periodic maintenance and online monitoring**: Regularly carry out maintenance checks on the pump, and consider using modern sensing technologies for condition monitoring in order to keep track of the bearing status in real time and prevent potential failures. Through the combined use of these methods, it is possible to effectively reduce damage to the bearings of long-shaft submersible pumps caused by water ingress, thereby extending the pump’s service life and maintenance interval. .

It’s best to recall this point: the service life of a new pump should be longer than that after maintenance. Given this, it should be a quality issue with the maintenance. Damage to the bearings caused by the initial shrinkage of the mechanical seal usually results in damage to the shaft surface, which is the interface between the mechanical seal and the shaft. Without further repair, the roughness of this shaft surface leads to leaks, thereby shortening the service life of the bearings. . . . . The structural flaw of this type of pump is that the mechanical seal is damaged first, which then leads to damage to the bearings; damage to the shaft surface occurs only when it is not detected in time. Therefore, during use, if any abnormal noises are heard, it is necessary to stop using it immediately for maintenance. To ensure a long service life, the smoothness of the shaft surface must be maintained during maintenance. It is best to regularly inspect and replace the machine seal. If modification is required, a water-sealing solution should be adopted, and the water-sealing technique used in slurry pumps can serve as a reference. For reference, the use of an air seal can generate high temperatures that may damage the mechanical seal.

Long-shaft submersible pumps generally do not use mechanical seals; instead, they rely on shaft sleeves and graphite liners for sealing. There are flushing ports in between these liners, and as long as these flushing ports are not blocked, the shaft sleeves and liners are less likely to get damaged. Filters and impeller flow meters can be added to the flushing water to monitor its flow rate; if the flow rate decreases, the filters should be cleaned.

The renovation solutions and preventive measures for bearing damage caused by water ingress in long-shaft submersible pumps focus on optimizing the sealing system, improving the design of the bearing chamber, upgrading materials, and enhancing operation and maintenance management. By comprehensively applying these measures, the risk of water ingress into bearings can be effectively reduced, the service life of the equipment can be extended, and operational reliability can be improved. In practical operation, it is necessary to select an appropriate approach based on the specific operating conditions and characteristics of the equipment.