A170-L 170-L32

Common issues

• Bearing wear (journal and thrust bearings, often due to oil contamination, insufficient lubrication, or imbalance).
• Compressor fouling (due to dirty intake air, leading to reduced efficiency, surging, and increased exhaust gas temperatures).
• Turbine fouling/erosion (due to poor fuel combustion, high exhaust gas temperatures, abrasive particles, or water washing issues, leading to reduced efficiency and potential blade damage).
• Nozzle ring deformation or cracking (thermal stress, foreign object damage, or erosion).
• Oil leakage from bearing housing (worn sealing rings, incorrect oil pressure, or blocked oil drain lines).
• Rotor imbalance leading to excessive vibration (due to fouling, blade damage, bearing wear, or foreign object ingestion).
• Surging (often linked to compressor fouling, engine load fluctuations, or operational issues).

Inspection checklist

• Bearing Clearances: Measure axial and radial clearances. Compare with manufacturer's specified new and wear limits. Look for signs of rubbing or excessive play.
• Rotor Condition: Visually inspect compressor and turbine wheels for fouling, erosion, cracks, foreign object damage, and tip rub marks. Check for any signs of imbalance.
• Nozzle Ring & Diffuser: Inspect for fouling, erosion, cracks, and deformation. Ensure gas passages are clear and uniform.
• Lubricating Oil System: Check oil supply pressure and temperature. Inspect oil filter condition. Look for oil leaks at bearing housing, connections, and drain lines.
• Air Filter (if applicable): Inspect the condition of the intake air filter elements for cleanliness and damage.
• Casing & Insulation: Check for cracks, hot spots, and integrity of thermal insulation on the exhaust gas casing. Ensure all covers and access points are securely fastened.
• Mounting & Connections: Verify security of turbocharger mounting bolts, exhaust gas inlet/outlet, air outlet, and oil pipe connections. Check for signs of stress or movement.
• Drainage System: Ensure water washing drainage system (if fitted) is clear and functional, preventing water accumulation.
• Vibration Monitoring: Check readings and trends from any installed continuous vibration monitoring system. Investigate any spikes or sustained high levels.

Service intervals

Typical wear limits

Ranges are typical for this design class. Always confirm against the manufacturer documentation for your serial number.

Critical spares

• Bearing cartridge assembly (complete set of journal and thrust bearings).
• O-rings, gaskets, and sealing rings (especially for bearing housing, gas/air sides, and casing joints).
• Lubricating oil filter elements.
• Air filter elements (if applicable to the specific installation).
• Nozzle ring segments (if modular design, or a complete nozzle ring).
• High-temperature bolts/studs for casing connections.
• Balancing weights (for minor rotor re-balancing).

Safety

• High Rotational Speed: Risk of rotor burst if overspeed occurs or due to severe imbalance/material fatigue. Ensure overspeed trip is functional and regularly tested.
• High Temperatures: Exhaust gas casing and components operate at extremely high temperatures (>500°C). Risk of severe burns. Ensure insulation integrity and avoid contact with hot surfaces.
• Pressurized Systems: Air and exhaust gas sides are under significant pressure. Oil system is also pressurized. Risk of leaks and associated hazards (e.g., hot oil spray, exhaust gas leaks).
• Hot Oil/Gas Leaks: Potential for fire hazard in case of oil spray onto hot surfaces or exhaust gas leaks into the engine room. Maintain strict vigilance for any leaks.
• Lifting & Handling: Large turbocharger components are heavy. Proper lifting gear, certified equipment, and adherence to safe lifting procedures are essential during maintenance to prevent injuries.

Class survey

The class surveyor will typically check the following: 1. Performance Verification: Review of engine room logbook entries for turbocharger speeds, exhaust gas temperatures (in/out), scavenge air pressure, and differential pressures across compressor/turbine to confirm normal and stable operation within design parameters. 2. Leakage Inspection: Thorough visual inspection for any oil, air, or exhaust gas leaks from the casing, connections, and drainage points. 3. Vibration Levels: Assessment of turbocharger vibration (visual, hand-held meter, or trend analysis from installed monitoring) to ensure it is within acceptable limits. 4. Maintenance Records: Review of the turbocharger's maintenance history, including dates of last overhaul, bearing replacements, cleaning cycles, and any reported defects or repairs. 5. Safety Devices: Verification of overspeed trip functionality (often by reviewing test records or witnessing a simulated test) and alarm settings. 6. General Condition: Inspection of casing integrity, insulation, mounting arrangements, and security of all securing bolts and connections. 7. Critical Spares: May inquire about the availability of critical spare parts onboard as per class requirements. 8. Link to Main Engine Survey: As a critical component of the main engine, its condition is often assessed in conjunction with the main engine's survey requirements, particularly during special or intermediate surveys.

Estimated lifetime: 80,000 - 120,000 running hours for major components (rotor shaft, casings) with regular overhauls and replacement of wear parts (bearings, seals, nozzle ring) as per service schedule. The turbocharger is designed to last the lifetime of the main engine if properly maintained and operated within parameters.