Bearing Disassembly and Maintenance Methods for Split Case Pumps

      As a core fluid transfer equipment, the single-stage double-suction split case centrifugal pump is widely used in water conservancy, chemical engineering, municipal engineering and other industrial sectors. Malfunctions are inevitable during long-term operation. Timely standardized maintenance and rapid troubleshooting are critical to ensuring continuous stable operation and extending the equipment’s service life. In this article, Changsha Zoomlian Pump Industry, a professional pump manufacturer, details the bearing disassembly methods for single-stage double-suction split case centrifugal pumps, as well as key maintenance requirements before startup, during operation and after shutdown.

      I. Two Professional Bearing Disassembly Methods

Bearing disassembly of the pump shall adopt standardized approaches based on installation structure variations, with the core principle of preventing damage from uneven stress on bearings or shafts.

1. Shaft End Disassembly Method

Prioritize using a dedicated bearing puller: firmly clamp the puller jaws onto the bearing inner ring, then apply uniform axial force to slide the bearing smoothly off the shaft. This method maximizes protection of bearing and shaft precision.  

If no puller is available, use a **wedge-tipped copper rod** (copper prevents component scratching): tilt the rod against the inner ring edge, strike evenly with a hammer, and rotate the rod slowly around the inner ring to ensure balanced force distribution until full removal.  

Alternative auxiliary support method: Clamp two equal-thickness steel plates symmetrically under the bearing inner ring, support the shaft stably with a cylinder/bracket (accommodating the shaft), pad the shaft top with a thick wooden/copper plate (to buffer impact), and strike vertically to dislodge the bearing axially.

2. End Cover Internal Disassembly Method

For pumps where the fit tolerance between the end cover bearing hole and bearing outer ring is smaller than that between the bearing inner ring and shaft, the bearing will be removed with the end cover. Disassemble the bearing from the end cover as follows:  

2.1 Place the end cover with its **spigot face upward**; pad wooden blocks around the outer side of the bearing hole (avoiding the bearing itself) to protect the end cover.  

2.2 Use a copper rod or special ejector pin (slightly smaller in diameter than the bearing outer ring) to press vertically against the outer ring end face, then strike downward evenly with a hammer until the bearing is ejected from the end cover hole.

      II. Pre-Startup Inspection Specifications

Complete the following checks to ensure safe startup and stable operation:

1. Manually rotate the coupling or pulley slowly to verify rotation direction matches design requirements. Ensure smooth rotation without jamming, abnormal vibration, or internal foreign objects; the bearing should turn freely.
2. Check belt drive tension (excessive slack causes slipping; excessive tightness accelerates bearing wear) and confirm coupling bolts are tightened.
3. Inspect all fasteners and connectors for secure attachment to prevent vibration-induced loosening during operation.
4. Clear debris around the pump unit to ensure unobstructed operation space.
5. Verify the suction pipe submergence depth meets design standards to avoid air ingress and idling.
6. For pumps equipped with a discharge valve: Close the valve before startup (reduces water resistance and motor startup load), and open it promptly after startup to resume normal operation.

III. In-Operation Monitoring Key Points

Continuously monitor operating parameters and equipment status post-startup; address abnormalities immediately to prevent fault escalation:

1. Ensure monitoring instruments (ammeter, pressure gauge, etc.) display stably. Operating current must stay within the motor’s rated range, and pressure gauge readings should remain within the design pressure interval without violent fluctuations.
2. Confirm discharge flow and pressure meet operating requirements; check for leakage at sealed joints (flange connections, shaft seals).
3. Shaft seal inspection:  

  3.1 Packing seal: Allow minimal leakage (10-20 drops per minute).  

  3.2 Mechanical seal: Leakage ≤10mL/h (≈3 drops per minute); adjust promptly if exceeded.

4. Bearing temperature monitoring: Rolling bearing temperature ≤75℃; sliding bearing temperature ≤70℃. Shut down immediately to inspect lubrication or assembly if temperatures rise continuously.
5. Monitor pump operation for abnormal noise (sharp sounds, impacts) or uneven vibration. Watch for sudden flow drops (indicative of suction pipe blockage or impeller scaling).
6. Real-time check of suction pipe submergence depth; adjust promptly if water level changes to maintain suction efficiency.
7. Regularly clean floating debris from the suction pipe trash rack to prevent clogging.

     IV. Shutdown & Post-Shutdown Maintenance Requirements

1. Shutdown procedure: Follow the "valve first, shutdown second" principle—close the discharge valve before cutting off motor power to prevent impeller/bearing damage from water backflow.
2. After each shutdown: Wipe oil/water residues from the pump body and pipelines to maintain cleanliness and facilitate detection of potential leaks or corrosion.
3. Winter operation: Drain all water from the pump body and pipelines immediately after shutdown to prevent freezing damage to components (pump body, impeller, seals).
4. Post-operating season maintenance:  

   4.1 Disassemble and inspect bearings for wear; replace aged lubricating grease.  

    Clean scale and debris from impellers and flow channels.  

    Inspect seals for integrity; replace if necessary.  

    Store equipment properly with dust and rust protection measures.