TCT70

Common issues

• Heavy turbine-side fouling, leading to reduced efficiency and increased exhaust back pressure.
• Rotor imbalance caused by uneven deposit accumulation on turbine or compressor blades, resulting in excessive vibration.
• Accelerated wear of journal and thrust bearings, often due to lubrication issues, high vibration, or extended service.
• Compressor efficiency loss, typically from fouling of diffuser and impeller, or damage to blades.
• Exhaust gas leakage from casing split lines, sealing rings, or pipe connections, posing safety and efficiency concerns.
• Lube oil system issues, such as low pressure, high temperature, contamination, or filter blockage, directly impacting bearing life.
• Vibrations exceeding manufacturer's limits, indicating underlying issues like imbalance, bearing wear, or foundation problems.
• Surge events, which can damage compressor blades and indicate engine/turbocharger mismatch or operational issues.

Inspection checklist

• Check for any exhaust gas or lube oil leakages from casing joints, seals, and pipe connections. Pay close attention to the gas outlet casing and bearing housing.
• Monitor and record turbocharger vibration levels (radial and axial) using onboard systems or portable equipment, comparing against manufacturer's acceptable limits.
• Inspect the condition of the air filter elements and ensure proper sealing. Visually check the compressor inlet for any signs of foreign object damage (FOD).
• Verify lube oil pressure and temperature are within specified operating ranges. Check oil quality, level, and the condition of lube oil filter elements.
• Measure rotor axial and radial clearances (play) during scheduled maintenance. Compare these values with the manufacturer's new and wear limits.
• During planned openings, visually inspect turbine and compressor blades for fouling, erosion, cracks, pitting, or foreign object damage.
• Check the condition of journal and thrust bearings for signs of wear, scoring, overheating, or abnormal clearances. Inspect bearing housings.
• Inspect the exhaust gas casing, nozzle ring, and diffuser for cracks, erosion, excessive carbon deposits, or distortion.
• Verify the proper functioning of the water washing system (if fitted), ensuring nozzles are clear and drain lines are unobstructed.
• Check the security of all foundation bolts, anti-vibration mounts, and support structures for integrity and tightness.

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 set of journal and thrust bearings (including sleeves/bushes if applicable).
• Labyrinth seals / sealing rings (gas side and oil side).
• Full gasket set for casing splits, exhaust gas connections, and bearing housing.
• Lube oil filter elements (main and pre-filters).
• Air filter elements (if applicable, often consumable).
• Water washing nozzles and associated O-rings/seals (if fitted).
• High-tensile bolts and nuts for critical casing connections.
• O-rings and small seals for service connections (e.g., oil inlet/outlet, pressure gauges).

Safety

• Extreme surface temperatures of the exhaust gas casing and associated piping, posing severe burn hazards. Always use appropriate PPE.
• Risk of exhaust gas leakage (containing CO and other toxic gases) from faulty gaskets or cracks, leading to asphyxiation or fire hazards.
• Danger from high-speed rotating components (rotor) during operation. Never open inspection covers or approach without ensuring the unit is stopped and cooled.
• Potential for sudden component failure (e.g., blade detachment) at high RPM, leading to projectile hazards and severe damage to surrounding equipment.
• Pressurized systems (lube oil, scavenge air, exhaust gas) require proper depressurization and isolation before any maintenance or inspection work.

Class survey

Class surveyors will typically verify the turbocharger's maintenance records, including running hours, previous inspections, and critical spare parts fitted. An external visual inspection for exhaust gas and lube oil leakages, casing integrity, and foundation security is standard. Operational parameters (RPM, temperatures, pressures, vibrations) will be checked against manufacturer's limits. For the 5-year special survey, an internal inspection of the rotor, bearings, nozzle ring, and diffuser for wear, damage, and clearances is usually required, unless an approved continuous survey scheme or condition monitoring program is in place. Verification of onboard critical spare parts inventory as per manufacturer and class requirements is also a key check.

Estimated lifetime: 16,000 - 24,000 running hours for a comprehensive major overhaul, with core components (rotor shaft, main casings) designed for 100,000+ hours with intermediate servicing and component replacement.