Routine maintenance and troubleshooting of vertical long-shaft pumps

Routine maintenance of vertical long-shaft pumps is crucial for maintaining their good operating condition and extending their service life. Regular maintenance and inspections allow for the timely detection of potential problems and the implementation of effective solutions, thereby preventing malfunctions and ensuring the stable operation of industrial circulating water systems. Specific routine maintenance methods and frequencies are as follows:

 

 

• Maintenance and care methods

 

Routine Maintenance：

1. Perform a visual inspection of the pump daily, checking the pump body, piping, valves, and other components for leaks, damage, or deformation.
2. Check the pump's operating sound for normalcy. If abnormal noise or vibration is detected, immediately stop the pump and investigate the cause.
3. Monitor the pump's inlet and outlet pressure, flow rate, and current, comparing them to normal operating data to determine if the pump is functioning correctly. Typically, pump operating parameters should fluctuate within the rated range-for example, flow rate fluctuations should not exceed ±5%, and pressure fluctuations should not exceed ±10%.

 

Weekly Maintenance：

1. Inspect the pump bearings weekly, measuring bearing temperature and vibration levels. Bearing temperature should generally not exceed 35°C above ambient temperature, and the maximum temperature should not exceed 80°C. Vibration levels should meet relevant standards; typically, at a speed of 1800 r/min, the effective vibration velocity should not exceed 4.5 mm/s.
2. Check the bearing lubrication condition, ensuring the lubricating oil level is normal and the oil quality is good. If the lubricating oil is found to be deteriorated or contaminated, it should be replaced immediately.

 

Monthly Maintenance：

1. Inspect the pump's sealing devices monthly, checking for leaks. For mechanical seals, the leakage rate should generally not exceed 5 drops per minute. If excessive leakage is found, check the wear of the sealing surfaces, the elasticity of the sealing springs, and the correct installation of the seals; replace the seals if necessary.
2. Inspect the pump impeller and pump body for wear. If any component is severely worn, repair or replace it promptly.

 

Quarterly Maintenance：

Clean the pump's inlet and outlet pipes quarterly, removing dirt, impurities, and sediment to ensure unobstructed flow.

At the same time, check that the pipe supports and hangers are secure. If any are loose or damaged, repair them immediately.

 

Annual Maintenance：

1. Perform a comprehensive overhaul of the water pump annually, including disassembling the pump body, inspecting all components for wear, corrosion, and damage, and replacing severely worn parts.
2. Readjust the pump shaft system and adjust the coupling clearance and concentricity.
3. Inspect and maintain the motor, including cleaning the motor interior, checking the winding insulation, and replacing the brushes.

 

• Common Faults and Troubleshooting

Vertical stainless steel long-shaft pumps may experience some common faults during operation, requiring timely resolution:

 

1. Insufficient Flow or No Water Discharge

Possible Causes: Clogged suction or discharge sides by debris (e.g., filter screen, impeller, guide vanes, discharge pipe, or valve system blockage).

Solution: Stop the pump, clean these components, and remove any blockages.

Possible Causes: Excessive wear of the sealing rings, leading to increased internal leakage and affecting flow.

Solution: Replace the sealing rings.

Other Causes: Impeller damage, incorrect rotation direction, low voltage, or insufficient immersion depth (leading to air intake).

Solution: Replace the impeller, correct the rotation direction, measure voltage and frequency to check the motor, or increase the suction water level.

 

2. Abnormal Vibration and Noise

Possible Causes: Insufficient suction water level or excessively large outlet gate valve opening, causing cavitation in the pump.

Solution: Increase the suction water level or decrease the opening of the outlet gate valve.

Possible cause: Impeller imbalance.

Solution: Correct the impeller's static balance.

Possible cause: Excessive shaft concentricity deviation (causing additional stress during pump operation, resulting in vibration).

Solution: Correct shaft concentricity and straighten the shaft.

Possible cause: Loose anchor bolts (causing unstable pump operation and vibration/noise).

Solution: Tighten the anchor bolts.

Possible cause: Worn or damaged bearings.

Solution: Replace the bearings.

 

3. Bearing overheating

Possible cause: Poor lubrication (e.g., insufficient, deteriorated, or contaminated lubricating oil).

Solution: Replenish or replace the lubricating oil promptly.

Possible cause: Improper bearing assembly (e.g., clearance too small or too large).

Solution: Readjust the bearing assembly clearance.

Possible cause: Excessive pump load (e.g., excessive flow rate or head, leading to increased bearing pressure).

Solution: Adjust the flow rate and head to reduce the load.

 

The maintenance and upkeep of vertical long-shaft pumps requires comprehensive consideration of multiple aspects, including daily inspection and monitoring, lubrication and sealing maintenance, cleaning and servicing, equipment adjustment and replacement, electrical and mechanical maintenance, and long-term shutdown and seasonal maintenance. Through scientific maintenance and upkeep measures, the normal operation of the long-shaft pump can be ensured and its service life extended.