AT23

Common issues

• Compressor fouling (due to contaminated intake air, oil carry-over from engine or turbocharger seals)
• Turbine-side fouling (from poor combustion, low-quality fuel, or exhaust gas bypass issues)
• Bearing wear (journal and thrust bearings, often indicated by increased axial/radial clearances, vibration, or oil analysis)
• Seal leakage (oil seals leading to oil in exhaust or compressor air, gas seals leading to reduced efficiency)
• Rotor imbalance (caused by uneven fouling, blade damage, or bearing wear, leading to excessive vibration)
• Foreign Object Damage (FOD) to compressor or turbine blades (from intake or exhaust stream)
• Nozzle ring/diffuser fouling or damage (reducing turbine efficiency and flow)
• Excessive vibration (a key indicator of underlying issues like imbalance, bearing wear, or blade damage)

Inspection checklist

• Visual inspection of compressor wheel for fouling, erosion, pitting, or FOD. Check for oil film on blades.
• Visual inspection of turbine wheel for fouling, erosion, cracks, or FOD. Check for carbon deposits.
• Check rotor axial and radial clearances using a dial gauge, comparing to manufacturer's specified limits (e.g., IHI AT23 manual).
• Inspect for oil leakage from bearing casing, oil drain lines, and compressor/turbine side seals.
• Check condition of air filter upstream of compressor for cleanliness and integrity.
• Inspect exhaust gas inlet and outlet ducts for leaks, cracks, or loose connections.
• Verify integrity and cleanliness of lubrication oil supply and drain lines to the turbocharger.
• Monitor turbocharger speed, exhaust gas temperatures (pre/post turbine), and boost pressure against normal operating parameters.
• Check tightness of all mounting bolts and connections (casing, support brackets, pipe flanges).
• Listen for unusual noises or observe for excessive vibration during operation.

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, and oil seals)
• Gasket set for casing, oil lines, and gas connections
• O-rings and sealing rings (various sizes for dismantling/assembly)
• Compressor wheel nut (specific to IHI AT23)
• Oil filter elements (if turbocharger has its own dedicated lubrication system)
• Cleaning nozzles/equipment for water washing

Safety

• High temperatures: Exhaust gas casing and turbine components operate at extremely high temperatures (up to 600°C+). Risk of severe burns. Ensure proper insulation and warning signs.
• High speed rotating parts: The rotor operates at tens of thousands of RPM. Catastrophic failure due to imbalance or bearing failure can cause projectile hazards. Never attempt to open while running.
• Pressurized air/gas: Compressor discharge and exhaust gas inlet are under significant pressure. Leaks can cause injury or damage. Always depressurize before working.
• Noise: Turbochargers generate high levels of noise. Hearing protection is mandatory in the vicinity.
• Hot oil: Lubrication oil can be hot and under pressure. Risk of burns or spray injury during maintenance.

Class survey

Class surveyors typically review the turbocharger's maintenance logbook entries, including dates of cleaning, bearing replacements, and major overhauls. They will visually inspect for external oil or exhaust gas leaks, check for excessive vibration during operation, and verify the integrity of safety devices (e.g., overspeed trip, if fitted). If the turbocharger is opened for scheduled maintenance during the survey, the surveyor may witness bearing inspections, clearance measurements (axial/radial), and general condition of the rotor and casings to ensure compliance with manufacturer's recommendations and class rules.