5S70ME-C10.5-GI

Common issues

• Gas Admission Valve (GAV) leakage or sticking due to carbon build-up, leading to poor combustion or gas slip.
• Pilot Fuel Injector (PFI) clogging or wear, particularly if operating extensively on gas, affecting pilot ignition.
• High-Pressure Fuel Gas Supply System (FGSS) component issues, such as leaks in piping, valve failures, or compressor/pump wear.
• Exhaust Valve burning, seat wear, or sticking, potentially exacerbated by varying combustion characteristics between HFO and LNG.
• Cylinder liner wear and scuffing, especially at the top land, requiring careful lubrication management for dual-fuel operation.
• Turbocharger fouling of compressor/turbine blades or bearing wear, impacting engine efficiency and scavenge pressure.
• Control system (ECS) faults or sensor failures specific to ME-GI operation, affecting gas mode stability or fuel changeover.
• Scavenge space fires or excessive carbon accumulation due to incomplete combustion or lube oil carry-over.

Inspection checklist

• **Fuel Gas Supply System (FGSS) Integrity**: Visually inspect all high-pressure gas lines, valves, and components for leaks (using leak detection spray or sniffers), proper insulation, and securing. Check pressure/temperature readings.
• **Gas Valve Units (GVU) & Gas Admission Valves (GAV)**: Inspect external condition for leaks, actuator function, and review operational data for abnormal opening/closing times or pressures.
• **Pilot Fuel Injectors (PFI)**: Check for external leakage. During overhaul, inspect nozzle holes for clogging and wear patterns.
• **Exhaust Valve Condition**: Review recent performance data (temperatures, opening/closing pressures). If accessible, inspect spindle and seat for signs of burning, pitting, or excessive wear. Check rotator function.
• **Cylinder Liner & Piston Condition**: Conduct scavenge port inspections for liner surface condition (scuffing, polishing), carbon build-up, and piston ring integrity. Review recent wear measurements and lube oil consumption.
• **Turbocharger**: Check axial and radial bearing play, inspect compressor and turbine blades for fouling or damage, and ensure air filter cleanliness.
• **Crankcase Safety Devices**: Verify functionality of oil mist detector, crankcase relief valves, and flame traps. Inspect crankcase for abnormal oil accumulation or water ingress.
• **Engine Control System (ECS) & Safety System**: Review alarm logs, test emergency stops, overspeed trip, and verify gas detection system functionality. Check fuel changeover sequence and interlocks.
• **Scavenge Space**: Inspect for cleanliness, excessive carbon deposits, oil accumulation, and proper drainage. Check scavenge port bars for damage.

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 Cylinder Cover with GAV and PFI (1 unit)
• Exhaust Valve Spindle and Seat Ring (1 set)
• Piston Rings (full set for one cylinder)
• Pilot Fuel Injectors (PFI) (1-2 units)
• Gas Admission Valve (GAV) components (seals, springs, or complete unit)
• High-Pressure Fuel Gas Pump/Compressor spare parts (seals, valves, bearings)
• Main Bearing / Connecting Rod Bearing shells (1 set of each)
• Turbocharger bearing cartridge or complete rotor assembly

Safety

• **Gas Leakage (LNG)**: Risk of fire, explosion, and asphyxiation from high-pressure LNG leaks. Ensure gas detection and ventilation systems are fully operational.
• **High-Pressure Gas System**: Operating pressures up to 300 bar for ME-GI pose significant hazards. Strict adherence to safety procedures during maintenance and operation is critical.
• **Fuel Changeover Risks**: Potential for engine trip, blackout, or uncontrolled combustion if changeover procedures between LNG and HFO are not executed correctly or if system malfunctions.
• **Crankcase Explosions**: Standard 2-stroke risk, potentially heightened by unburnt fuel accumulation or poor combustion in gas mode. Ensure oil mist detector and relief valves are functional.
• **Cryogenic Hazards**: Contact with LNG can cause severe frostbite. Proper PPE and emergency procedures for LNG spills are essential.

Class survey

Class surveyors will rigorously inspect the Fuel Gas Supply System (FGSS) for compliance with IGF Code, including double-wall piping integrity, gas detection, ventilation, ESD (Emergency Shut Down) systems, and inerting arrangements. Functionality tests of all engine safety devices (overspeed, low lube oil pressure, high cooling water temp, engine trips) and the fuel changeover system are critical. They will review planned maintenance system (PMS) records, defect reports, and overhaul reports for critical components like cylinder units, exhaust valves, and turbochargers. Scavenge space and under piston space cleanliness will be checked. Specific attention will be paid to the condition and operational parameters of ME-GI specific components such as Gas Valve Units (GVU) and high-pressure gas pumps/compressors. Overall engine cleanliness, absence of leaks, and general operational readiness are also key.