TCT

Common issues

• Nozzle ring and turbine blade fouling from exhaust deposits, leading to reduced efficiency and increased exhaust back pressure.
• Compressor wheel and diffuser fouling, causing reduced scavenge pressure and engine performance degradation.
• Bearing wear (axial and radial) due to contaminated lube oil, insufficient oil supply, or excessive vibration.
• Rotor imbalance, often initiated by deposit release from blades or minor impact damage, leading to high vibration.
• Labyrinth seal wear, resulting in oil leakage into the exhaust or compressor side, or gas bypass.
• Exhaust gas leaks from casing joints, expansion bellows, or turbine outlet due to thermal stress or gasket failure.
• Abnormal noise or vibration indicating internal component damage or imbalance.

Inspection checklist

• Visual inspection for oil leaks (bearings, casing joints) and exhaust gas leaks (turbine casing, expansion bellows).
• Check for abnormal noise (whining, grinding) or excessive vibration during operation (use vibration meter if available).
• Inspect compressor wheel and diffuser for fouling, erosion, or foreign object damage (FOD) after cleaning.
• Inspect turbine blades and nozzle ring for fouling, erosion, cracks, or impact damage after cleaning.
• Check axial float and radial play of the rotor shaft (if accessible or during minor overhaul) against manufacturer's limits.
• Verify integrity of air filter and charge air cooler for cleanliness and damage.
• Inspect lube oil supply and drainage lines for proper flow, pressure, and cleanliness.
• Check exhaust gas casing insulation for integrity and signs of hot spots.
• Confirm overspeed trip device functionality (if testable without full shutdown, otherwise verify last test record).
• Review operational parameters (speed, exhaust gas temp, charge air temp/press) against manufacturer's specifications.

Service intervals

Typical wear limits

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

Critical spares

• Complete bearing assembly (thrust and radial bearings, including bearing bushes and thrust collar).
• Labyrinth seals (both compressor and turbine side).
• Gasket sets and O-rings for casing joints and connections.
• Impeller nut (for compressor wheel).
• Air filter elements (if specific to turbocharger intake).
• Overspeed trip sensor or mechanical trip components (if applicable).

Safety

• High surface temperatures of the turbine casing and exhaust gas piping, requiring proper insulation and guarding.
• Extremely high rotational speeds of the rotor (up to 100,000+ RPM), posing a severe hazard in case of component failure.
• High pressure in the charge air system, requiring careful depressurization before opening.
• Potential for hot oil spray from leaks under pressure, leading to fire hazard or burns.
• Risk of foreign object ingestion during operation or maintenance, causing catastrophic damage.

Class survey

Class surveyors typically check the overall external condition for leaks (oil, exhaust gas), proper insulation, and securing arrangements. They verify that operational parameters (speed, temperatures, pressures) are within manufacturer's limits and that maintenance records, including overhauls and overspeed trip tests, are up-to-date. Availability of critical spare parts onboard and compliance with ISM code requirements for machinery maintenance are also assessed.