Common issues
- Mechanical seal develops leakage or weepage over time from normal wear
- Impeller and wear plate erode from debris typical of bilge service, reducing flow and head
- Coupling misalignment develops after maintenance work, causing vibration and premature bearing wear
- Suction strainer or strum box blocks with debris, causing cavitation or loss of prime
- Motor bearings fail from water ingress if the shaft seal has been leaking undetected
- Casing corrodes or erodes over time in continuous seawater service
Inspection checklist
- Check the mechanical seal for leakage or weepage
- Check coupling alignment and condition
- Carry out a vibration check and compare to baseline
- Inspect and clean the suction strainer/strum box
- Perform an insulation resistance test on the motor
- Monitor bearing temperature during operation
- Visually inspect the casing for corrosion or erosion
- Verify non-return and isolation valves in the pump line operate correctly, and check pump performance against the design curve during a routine test
Service intervals
| Mechanical seal inspection | at each dry-docking, or per the running-hour interval in the manufacturer's manual |
|---|
| Bearing lubrication/grease or oil change | per the manufacturer's manual - confirm current interval |
|---|
| Coupling alignment check | annually, or after any work disturbing the pump or motor |
|---|
| Strainer cleaning | per operational routine, more frequently in debris-heavy service |
|---|
| Insulation resistance test | every 6-12 months |
|---|
Typical wear limits
| Impeller/wear ring running clearance | centrifugal pumps of this size class are typically renewed once clearance reaches roughly two to three times the original design clearance, commonly a few tenths of a millimetre - confirm the specific limit in DESMI's own manual |
|---|
Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.
Critical spares
- Mechanical seal kit
- Impeller
- Wear ring/wear plate
- Shaft sleeve
- Coupling element
- Bearing set
Safety
- Bilge water handled by this pump may be oil-contaminated - route discharge per MARPOL/oily water separator requirements, not directly overboard
- Coupling guard must be in place before running the pump
- Isolate power and confirm the shaft is stopped before opening the casing or working on the coupling
- Relieve system pressure before opening the casing for maintenance
Class survey
Bilge and ballast pumping arrangements are checked under the vessel's bilge/ballast system survey; the surveyor verifies pump capacity against the approved bilge/ballast calculation, checks non-return valves and remote valve operation where fitted, and confirms the pump is included in the planned maintenance system with test records available.