Stern Tube Seal Renewal Procedure in Dry Dock
Preparation Phase
System Familiarization
- Check maker’s instruction manual for key points, draining procedures, and service records
- Review previous records (dry dock reports, seal renewal records, wear down reports)
- Verify and update TALISHAFT MONITORING records
- Prepare dry dock specification and maintenance plan for office approval
Equipment and Supplies
- Check onboard spares and raise requisitions if needed
- Ensure sufficient environmentally acceptable lubricant (EAL) is available
- Verify safety equipment availability (gloves, helmets, safety harnesses)
Pre-Work Checks
- Review previous lubricating oil (LO) analysis results
- Check main engine crankshaft deflection and bearing clearances
- Verify onboard LO analysis records
Execution Phase
Safety Measures
- Conduct risk assessment before starting work
- Hold toolbox meeting with dock supervisor and service team
Initial Inspections
- Turn shaft to zero marking and check clearance
- Isolate and drain the system
- Measure propeller drop/stern tube wear down clearance using poker gauge
- Compare readings with previous records and maker’s limits
Chrome Liner Inspection
Check for:- Wear down
- Scoring marks
- Cracks
Seal Replacement
- Decide whether to change seal in-situ or remove propeller
- If propeller is removed, inspect stern tube bearing for:
- Lacquer formation
- Signs of overheating
- Fretting marks
- Metal peeling
Reassembly and Testing
- Pay attention to alignment of stern tube and propeller shaft
- Replenish lubricating oil and conduct leak test
- Recheck poker gauge reading at ZERO mark with all main engine units in place
Key Points to Remember
- Perform leak test after flushing pipes
- Take wear-down readings before and after overhauling AFT seal
- Protect seals from external damage (sandblasting, painting, welding, chemicals, heat)
- Use stainless steel fitting bolts (SUS 316 or equivalent) for AFT seal installation
- Secure all fitting bolts and plugs with stainless steel wire
- Return all valves to “Normal Operating Condition” after testing
- Monitor oil level for sudden reduction due to air-locking dissolution
