SD 48SD

Common issues

• Bearing wear (journal and thrust bearings) leading to increased axial/radial play and vibration.
• Turbine side fouling (nozzle ring, turbine blades) due to HFO combustion, reducing efficiency and increasing exhaust gas back pressure.
• Compressor side fouling (impeller, diffuser) from intake air contaminants, reducing air flow and pressure.
• Oil leakage from bearing housings or oil supply/drain lines, indicating seal wear or pipe integrity issues.
• Rotor imbalance due to uneven fouling or minor blade damage, causing excessive vibration and potential bearing failure.
• Exhaust gas casing cracks or leaks, particularly around expansion joints or high-stress areas.
• Surging, often caused by engine load changes, air filter blockage, or severe fouling, leading to unstable operation.

Inspection checklist

• Check axial and radial play of the rotor shaft (cold condition) against manufacturer's limits.
• Visually inspect compressor impeller and diffuser for fouling, erosion, or foreign object damage (FOD).
• Visually inspect turbine blades and nozzle ring for fouling, erosion, cracks, or burning (after opening casing).
• Inspect bearing oil inlet/outlet temperatures and pressures, and check for any oil leaks.
• Check integrity of exhaust gas casing, insulation, and expansion bellows for cracks or leaks.
• Verify functionality of compressor and turbine washing systems (if fitted).
• Monitor turbocharger RPM, boost pressure, and exhaust gas temperatures (in/out) against engine load and design parameters.
• Inspect air filter condition and ensure proper sealing and cleanliness.
• Check security of turbocharger mounting bolts and foundation.

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 (cartridges or individual components).
• Full set of O-rings, gaskets, and seals for bearing housing and casing openings.
• Oil filter elements (if applicable to the T/C's lubrication system).
• Compressor wheel nut and locking plate.
• Nozzle ring segments or complete nozzle ring (depending on design and criticality).
• High-temperature bolts and nuts for casing connections.

Safety

• High surface temperatures of the exhaust gas casing and associated piping (burn hazard).
• High rotational speeds of the rotor (up to 15,000-20,000 RPM for this size), posing a risk of rotor burst if overspeed occurs or material fatigue is present.
• Pressurized hot oil in the lubrication system (burn and slip hazard).
• Noise levels during operation can exceed safe limits, requiring hearing protection.
• Potential for exhaust gas leakage, leading to toxic atmosphere or fire risk in enclosed spaces.

Class survey

Class surveyors typically verify the following: Visual inspection of the turbocharger external casing for any signs of exhaust gas or oil leaks, cracks, or excessive corrosion. Confirmation of maintenance records, including dates of last major overhaul, bearing renewals, and cleaning. Review of logbook entries for consistent performance parameters (RPM, boost pressure, temperatures) to ensure efficient operation. Inspection of safety devices such as overspeed trip mechanism and alarm settings. Verification of secure mounting and integrity of foundation bolts. Inspection of exhaust gas piping, expansion joints, and insulation for leaks or damage. On occasion, a request for opening the compressor or turbine side for internal inspection may be made if performance issues are suspected or as part of a planned machinery survey.

Estimated lifetime: 36,000 - 48,000 hours before major component replacement (e.g., rotor shaft, casings) may be considered, assuming regular maintenance and overhauls. The core design is for the engine's lifetime, but major overhauls are critical to achieve this.