AT AT-29

Common issues

• Bearing wear (journal and thrust bearings) leading to increased clearances, vibration, and potential rotor contact.
• Compressor fouling due to dirty intake air or oil carry-over, reducing air flow and efficiency, leading to surging.
• Turbine fouling (carbon deposits, ash) from poor combustion or heavy fuel operation, reducing turbine efficiency and increasing exhaust back pressure.
• Oil leakage from compressor or turbine side due to worn labyrinth seals, blocked oil drain, or excessive bearing clearance.
• Rotor imbalance and vibration caused by fouling, bearing wear, or foreign object damage to blades.
• Nozzle ring erosion or damage (e.g., from foreign objects), affecting turbine efficiency and exhaust gas flow.
• Cracks in turbine casing or exhaust gas manifold due to thermal stress cycling or vibration.
• Turbocharger surging, often linked to engine load, fouling, or incorrect matching.

Inspection checklist

• Monitor bearing temperatures (inlet/outlet oil, bearing housing) and ensure they are within manufacturer's limits (typically <90°C).
• Check oil inlet pressure (typically 1.5-3.0 bar) and outlet temperature (typically 60-75°C) for the turbocharger lubrication system.
• Listen for abnormal noises (whining, grinding) and check for excessive vibration using a vibration meter or by hand-feel on the casing.
• Visually inspect compressor wheel for fouling, erosion, or damage through the inspection port. Check for oil film on blades.
• Visually inspect turbine wheel and nozzle ring for fouling, erosion, or damage through the inspection port (if accessible and safe).
• Verify free flow of the oil drain pipe; check for any signs of oil contamination or sludge.
• Check air filter condition for cleanliness and integrity; ensure no bypass of unfiltered air.
• Inspect all casing bolts, clamps, and connections for tightness and signs of exhaust gas or oil leakage.
• Record boost pressure, exhaust gas temperature before and after turbine, and differential pressure across the turbine for performance analysis.

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 cartridge set (journal and thrust bearings)
• Labyrinth seal rings (compressor and turbine side)
• Gasket and O-ring sets for casing, oil lines, and inspection covers
• Oil filter elements (if TC has dedicated oil filtration)
• Nozzle ring (especially if operating on heavy fuel oil or known for erosion)
• Mounting bolts and locking washers for casing sections
• Emergency repair kit for minor oil leaks (e.g., sealing compound, clamps)

Safety

• High surface temperatures of turbine casing and exhaust gas piping (can exceed 400°C); ensure insulation is intact and personnel are aware.
• High rotational speeds (up to 20,000-30,000 RPM for this size); risk of rotor burst if overspeed or severe imbalance occurs.
• Pressurized air (boost air) and hot exhaust gases; ensure all connections are secure to prevent blowouts.
• Hot lubricating oil under pressure; risk of burns and fire if leaks occur.
• Noise levels during operation are extremely high; hearing protection is mandatory in the vicinity.

Class survey

Surveyors will typically check the general condition, cleanliness, and absence of oil/gas leaks. They will review operational logs for bearing temperatures, oil pressures, boost pressure, and exhaust gas temperatures to ensure stable operation. Evidence of routine maintenance (washing, filter changes) and spare parts availability will be checked. The integrity of insulation, safety guards, and overspeed trip functionality (if fitted and testable) are also key points. Any abnormal noise or vibration will warrant further investigation. Documentation such as the IHI manual and service reports should be readily available.

Estimated lifetime: 16,000-24,000 running hours before major overhaul (requiring full disassembly, inspection, and likely bearing/seal replacement). Total structural life of casings can exceed 80,000 hours with proper maintenance.