Horizontal single-stage double-split casing centrifugal pumps are widely applied in various industries and play an indispensable role. Timely maintenance upon faults, early detection and resolution of defects are essential to sustain steady and reliable operation of the equipment.
I. Two Main Bearing Disassembly Methods
Bearings can be disassembled either inside the end cover or directly from the rotating shaft.
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Disassembly from the rotating shaft: Pull the bearing off the shaft with a dedicated bearing puller. If a puller is unavailable, use a wedge-tipped copper rod to prop against the bearing inner ring at an inclined angle. Strike the copper rod with a hammer while moving it around the inner ring to ensure uniform force distribution around the bearing until it is knocked free. An alternative approach is to clamp the bearing under its inner ring with two thick steel plates, support the assembly with a cylinder or bracket that accommodates the shaft, place a thick wooden or copper plate on the top end of the shaft, and strike the plate to remove the bearing.
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Disassembly inside the end cover: The fit between the bearing outer ring and the bearing bore of some end covers is tighter than the fit between the bearing inner ring and the shaft. For such cases, leave the bearing seated in the end cover bore when removing the end cover. Place the end cover flat with its spigot surface facing upward, lay wooden blocks around the bearing bore (ensure the blocks do not press against the bearing itself). Take a copper rod or other metal rod with a diameter slightly smaller than the bearing outer diameter, press it against the bearing outer ring, and hammer the rod downward from above to knock the bearing out of the bore.
Pre-Start Inspection for Safe Pump Operation
Conduct complete inspections before startup to guarantee safe operation:
- Rotate the coupling or pulley slowly by hand to verify correct rotation direction, smooth and flexible rotation, absence of foreign objects inside the pump, normal bearing operation, and proper belt tension.
- Check that all bolts are tightly fastened.
- Clear any debris around the pump unit that may hinder operation.
- Confirm sufficient submergence depth of the suction pipe.
- Close the discharge valve to lower startup load; remember to open the valve promptly after startup.
Post-Startup Inspection Items
After starting the pump, inspect all instruments for stable and normal readings:
- Operating current shall not exceed the rated value, and the pressure gauge reading shall stay within the designed range.
- Check normal water discharge from the horizontal split casing pump and leakage at all parts of the unit.
- Adjust packing gland compression: a slight leakage of 10 to 20 drops per minute is acceptable for packing seals; the leakage rate of mechanical seals shall not exceed 10 mL/h (approximately 3 drops per minute).
- Temperature limits: rolling bearings ≤75°C; plain bearings ≤70°C.
- Listen for abnormal noises and observe abnormal vibration; monitor any reduction in water output.
- Adjust the submergence depth of the suction inlet as required.
- Regularly clear floating debris on the trash rack.
- For belt-driven units, check for belt slippage.
Precautions for Pump Shutdown and Post-Shutdown Maintenance
- Before shutting down the pump, close the discharge valve first to prevent backflow and component damage.
- After each shutdown, wipe oil stains off the pump casing and pipelines to keep the unit clean and facilitate early identification of potential faults.
- Drain all water completely after shutdown in winter to prevent cracking of the pump casing and internal components caused by freezing.
- Perform comprehensive maintenance at the end of each operating season.
