Daily Maintenance and Care Methods for Screw Pumps

Daily maintenance and upkeep of screw pumps are central to extending equipment lifespan and ensuring stable operation. This requires a three-pronged approach encompassing operational inspections, periodic maintenance, and shutdown maintenance. Key maintenance points vary slightly across different screw pump types, with specific methods outlined below:
I. Daily Operational Inspections (Per Shift / Daily)
Operational Status Monitoring
Listen for abnormal noises during pump operation. Normal operation should be free of unusual sounds, impact noises, or sharp friction. Immediately shut down and investigate if unusual sounds occur (possibly indicating abnormal screw meshing, bearing damage, or stator wear).
Check pressure and flow rate. Significant pressure fluctuations or sudden flow drops may indicate suction line blockage, stator wear, or safety valve failure. Address promptly.
Monitor pump body and motor temperatures. Bearing temperatures must not exceed 75°C. Motor temperature rise must comply with nameplate specifications. Shut down for cooling and inspect lubricant levels or heat dissipation if temperatures are excessively high.
Seal and Leak Inspection
Inspect shaft seal areas (packing seal / mechanical seal). No significant leakage is permitted: Packing seals allow minimal dripping (3-5 drops per minute), while mechanical seals must show no visible leakage.
Inspect pump flanges and inlet/outlet pipe connections. Tighten bolts or replace gaskets immediately if media leakage occurs.
Lubrication System Inspection
For twin-screw and triple-screw pumps, regularly check lubricant levels. Maintain oil between 1/2 to 2/3 of the dipstick mark. Oil must be clear, free of emulsification, and devoid of contaminants.
For single-screw pumps, inspect the grease condition in the coupling bearings. Replenish or replace grease if it appears dried out or clumped.
II. Regular Maintenance (Performed Based on Operating Hours/Cycle)
Short-Term Maintenance (Weekly/Monthly)
Clean dust and oil stains from the pump body surface and surrounding area to maintain equipment cleanliness and prevent dust ingress into bearings or motors.
Inspect the suction filter and promptly clean the filter screen (especially for single-screw pumps handling particulate-laden media) to prevent clogging that could cause cavitation or air entrainment.
Tighten all connecting bolts between the pump body, motor, and base to prevent loosening due to vibration.
Mid-Term Maintenance (Every 3-6 Months)
Replace lubricating oil/grease: For twin/ Replace lubricating oil in gearboxes and bearing housings of twin/triple screw pumps with compatible oil (select type based on medium temperature, e.g., mineral or synthetic oil); replace lithium-based grease in single screw pump bearings.
Inspect mechanical seals: Replace moving and stationary rings promptly if seal surfaces show wear or cracks; adjust packing gland tightness for gland seals, replacing packing when severely worn.
Calibrate Safety Valves and Pressure Gauges: Ensure safety valve trip pressure accuracy and pressure gauge readings precision to prevent pump damage from overpressure operation.
Long-Term Maintenance (Annual / Overhaul Cycle)
Disassemble pump for comprehensive inspection:
- For single-screw pumps, inspect rotor and stator wear. Replace both components as a matched pair if stator bore shows grooves or rotor surface exhibits severe wear. For twin/triple screw pumps, inspect screw meshing clearance. Replace screws if clearance is excessive.
Test motor insulation performance. Inspect windings for moisture or aging; dry if necessary.
Inspect coupling elastic pads. Replace immediately if cracked or deformed to ensure smooth transmission.
III. Shutdown and Storage Maintenance
Short-term shutdown (days to one week)
For pumps handling easily solidifying media (e.g., asphalt, paraffin), flush the pump cavity with clean water or solvent after shutdown to prevent solidification and blockage.
Keep the pump cavity filled with media or rust inhibitor to prevent dimensional changes in mating clearances due to rotor/stator drying and shrinkage.
Long-Term Shutdown (Over One Month)
Thoroughly disassemble the pump body. Clean components including rotors, stators, and pump casings to remove residual media and contaminants.
Apply rust-preventive oil to metal parts (rotors, pump shafts). Store stators separately in a cool, dry location, avoiding direct sunlight and compression deformation.
Implement moisture-proof measures for the motor, cover it with a dust cover, and periodically rotate the shaft (1-2 revolutions weekly) to prevent bearing corrosion and rotor deformation.
IV. Additional Maintenance Points for Special Conditions
Conveying Corrosive Media:
Select corrosion-resistant seals and lubricants. Regularly inspect the pump lining integrity to prevent media corrosion of the casing.
Conveying media containing solid particles: Shorten inspection cycles for the stator and rotor, and increase filter cleaning frequency to prevent accelerated wear caused by particles.
High-temperature operation: Use high-temperature resistant stator materials (e.g., fluororubber) and high-temperature lubricants. Enhance temperature monitoring to prevent component aging and failure.