MET-SR

Common issues

• Compressor fouling (reduced efficiency, surging, increased exhaust temperature)
• Turbine fouling (reduced efficiency, high exhaust gas temperature, increased back pressure)
• Bearing wear (increased axial/radial clearances, vibration, noise, potential for rotor contact)
• Rotor imbalance (excessive vibration, bearing damage, reduced component life)
• Oil leaks (from bearing casing, oil supply/drain lines, leading to oil consumption and fire risk)
• Foreign object damage (FOD) to compressor or turbine blades (from intake air or exhaust gas)
• Cracks in casing components (especially exhaust gas side due to thermal stress)
• Surging (unstable operation, often due to fouling, air filter blockage, or engine issues)

Inspection checklist

• Visual Inspection (External): Check for oil leaks, exhaust gas leaks, cracks in casing/insulation, loose connections, proper securing of components.
• Rotor Free Play (Axial & Radial): Measure and record clearances. Compare with manufacturer's limits. This is a primary indicator of bearing health.
• Compressor & Turbine Blade Condition: Inspect for fouling, erosion, pitting, cracks, or foreign object damage (FOD). Use boroscope for internal inspection if necessary.
• Bearing Condition (if opened for service): Check for scoring, discoloration, excessive wear on journal and thrust bearings. Inspect bearing housing for damage.
• Lubricating Oil System: Verify correct oil level, pressure, and temperature. Inspect oil filters for clogging and ensure proper oil supply/drainage.
• Air Filter Condition: Inspect air intake filter for clogging, damage, or bypass, which can lead to compressor fouling.
• Operational Parameters: Monitor boost pressure, exhaust gas temperatures (before and after turbine), turbocharger RPM, and vibration levels during engine operation.
• Nozzle Ring & Diffuser Condition: Inspect for fouling, erosion, or damage, which impacts efficiency and gas flow.

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 / Complete Bearing Set (Journal and Thrust Bearings)
• Sealing Rings (Labyrinth seals, gas seals)
• O-rings and Gaskets (for casing, oil lines, critical connections)
• Oil Filter Elements
• Nozzle Ring (if prone to wear/fouling in specific applications)
• Service Kit (minor seals, bolts, washers for routine maintenance)

Safety

• High Temperatures: Exhaust gas casing and turbine components operate at extremely high temperatures (300-600°C). Risk of severe burns. Ensure insulation integrity.
• High Rotational Speed: Rotor operates at very high RPM (up to 30,000-60,000 RPM). Catastrophic failure due to imbalance or bearing failure can cause casing rupture and projectile hazards.
• Pressurized Air/Gas: Compressor discharge and exhaust gas inlet are under pressure. Risk of injury from sudden depressurization or leaks during maintenance.
• Hot Lubricating Oil: Lubricating oil can be hot and under pressure, posing burn and slip hazards.
• Heavy Components: Maintenance involves lifting heavy components. Proper lifting gear and procedures are essential to prevent injury.

Class survey

During annual or special surveys, the class surveyor typically checks: 1. Documentation: Verification of maintenance records, service reports, spare parts inventory, and previous survey reports. 2. Operational Check: Witnessing the turbocharger in operation, monitoring key parameters (boost pressure, exhaust temperatures, RPM, vibration) to ensure stable performance. 3. External Visual Inspection: Checking for oil/exhaust gas leaks, cracks in casing, proper insulation, secure mounting, and general cleanliness. 4. Safety Devices: Verification of overspeed trip (if fitted) and alarm functions. 5. Bearing Clearances: If the turbocharger is opened for scheduled maintenance during the survey window, the surveyor will typically witness or review the measurement of axial and radial clearances. 6. Air Filter Condition: Inspection of the air intake filter. 7. Compliance: Ensuring maintenance aligns with manufacturer's recommendations and class requirements.

Estimated lifetime: 80,000 - 120,000 running hours (with diligent maintenance and timely overhauls, some units exceed this significantly)