NA-L NA80/L

Common issues

• Bearing wear (journal and thrust) leading to increased rotor axial and radial play, often indicated by vibration or oil leakage.
• Compressor fouling due to dirty intake air, resulting in reduced air delivery, lower boost pressure, and potential surging.
• Turbine fouling or erosion from poor fuel combustion or abrasive particles in exhaust gas, causing reduced efficiency and higher exhaust gas temperatures before turbine.
• Oil leakage from bearing housing seals (labyrinth or mechanical) due to wear, blocked oil drains, or excessive bearing clearances.
• Nozzle ring distortion, cracking, or erosion, impacting turbine efficiency and exhaust gas flow.
• Rotor imbalance caused by fouling, blade damage, or bearing wear, leading to excessive vibration and accelerated component degradation.
• Casing cracks or deformation, particularly in the exhaust gas side, due to thermal stress or mechanical impact.

Inspection checklist

• Measure rotor axial and radial play, comparing against manufacturer's specified wear limits (e.g., axial max 0.35-0.45mm, radial max 0.20-0.25mm for this class).
• Visually inspect compressor wheel and diffuser for fouling, erosion, foreign object damage (FOD), and blade integrity.
• Visually inspect turbine blades, nozzle ring, and gas inlet casing for fouling, erosion, cracks, and thermal deformation.
• Check for any signs of oil leakage from the bearing casing, oil drain lines, and air/gas side seals.
• Inspect the air filter elements for cleanliness and damage; ensure proper sealing.
• Verify the integrity of the exhaust gas casing, insulation, and expansion bellows for cracks or gas leaks.
• Check the condition and security of all mounting bolts, foundations, and pipe connections.
• Ensure all turbocharger drains (oil and washing water) are clear and functioning correctly.
• Monitor and trend bearing temperatures (if sensors are fitted) and turbocharger speed for anomalies.

Service intervals

Typical intervals for this design class, not the manufacturer’s figures for your model. The manufacturer’s manual is binding.

Typical wear limits

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

Critical spares

• Complete bearing set (journal bearings, thrust bearing, thrust collar)
• Oil sealing rings (labyrinth seals for compressor and turbine sides)
• O-rings and gaskets for casing covers, oil inlet/outlet, and washing connections
• Air filter elements (if applicable for intake design)
• Lubricating oil pump and filter elements (if unit has a dedicated lube oil system)
• Nozzle ring segments (if design allows for segment replacement)
• Complete rotor cartridge (for emergency replacement or major overhaul, often a shipyard stock item)

Safety

• Risk of catastrophic burst due to overspeed or severe rotor imbalance, potentially causing severe injury or damage.
• Extremely hot surfaces (exhaust gas casing, turbine outlet, associated piping) reaching 400-600°C, posing severe burn hazards.
• High noise levels (typically 100-120 dB) requiring mandatory hearing protection in the vicinity.
• Pressurized air and exhaust gas within the casings and piping, posing risk during dismantling or if leaks occur.
• Oil mist/vapor leakage onto hot surfaces, presenting a significant fire hazard.

Class survey

The class surveyor will typically check the general condition and cleanliness of the turbocharger, ensuring no excessive oil or exhaust gas leaks. They will verify the security of foundations, casing bolts, and pipe connections. Maintenance records for routine services, bearing replacements, and major overhauls will be reviewed to ensure compliance with maker's recommendations. Performance parameters (boost pressure, exhaust temperatures, bearing temperatures) from logbooks may be checked. During special surveys or if performance issues are reported, the surveyor may request rotor axial and radial play measurements or a visual inspection of the compressor/turbine wheels if covers are opened for other maintenance.

Estimated lifetime: 16,000 to 24,000 running hours for major overhaul of the rotor cartridge, with proper maintenance extending overall unit life significantly.