8S70ME-C10.5-GI

Common issues

• High-pressure gas admission valve (GAV) leakage or sticking, leading to poor combustion or gas slip.
• Exhaust valve burning or seat wear, particularly when operating on HFO or during frequent fuel changeovers.
• Cylinder liner scuffing or excessive wear, often linked to inadequate lubrication (especially with varying fuel types) or poor combustion.
• Issues with the Fuel Gas Supply System (FGSS), such as high-pressure gas pump (HPGP) failures, filter clogging, or gas line leaks.
• Turbocharger surging or reduced efficiency due to fouling or bearing wear, impacting scavenging and combustion.
• Control system (ME-GI specific) faults, sensor failures, or software glitches causing operational restrictions or shutdowns.
• Fuel oil injection system (FIVA valves, fuel pumps) malfunctions when operating on HFO, leading to poor atomization or misfires.
• Scavenge space fires or excessive carbon deposits due to unburnt fuel or lube oil accumulation.

Inspection checklist

• **Visual Inspection for Leaks:** Check all fuel lines (HFO and HP Gas), lube oil lines, cooling water lines, and exhaust gas piping for any signs of leakage. Pay close attention to gas valve train (GVT) and gas admission valve (GAV) areas.
• **Scavenge Space Condition:** Inspect scavenge ports and space for carbon deposits, oil accumulation, and proper drainage. Check for signs of blow-by or scavenge fires.
• **Crankcase Inspection (via doors):** Check main and connecting rod bearings for signs of overheating or abnormal wear (discoloration, scoring). Inspect crankshaft for visible defects and check oil mist detector functionality.
• **Exhaust Valve Actuation & Condition:** Observe exhaust valve operation (hydraulic system, timing). Listen for abnormal noises. If possible, check valve spindle and seat condition during planned maintenance.
• **Turbocharger Condition:** Inspect compressor and turbine blades for damage, fouling, or rubbing. Check bearing play (if accessible) and listen for abnormal noises. Verify charge air cooler cleanliness.
• **Fuel Gas System Integrity:** Verify the integrity of high-pressure gas piping, fittings, and quick-closing valves. Check gas detection system calibration and functionality. Inspect gas block and bleed valves.
• **Control System & Alarms:** Review engine control system (ECS) logs for active or historical alarms, abnormal operating parameters, and performance trends. Verify emergency shutdown (ESD) system functionality.
• **Cylinder Unit Performance:** Monitor exhaust gas temperatures (EGTs) and cylinder pressures (MIP) for consistency across all cylinders. Look for deviations indicating combustion issues.
• **Lubrication System:** Check lube oil levels, pressures, and filtration system. Inspect cylinder lubricators for proper function and dosage settings.

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 HFO Fuel Valves (at least 1 per cylinder)
• Complete set of Gas Admission Valves (GAVs) (at least 1 per cylinder)
• Exhaust Valve Spindle and Seat (at least 1 complete unit)
• Piston Rings (complete set for at least 1 cylinder)
• Cylinder Liner O-rings and sealing rings
• High-Pressure Gas Pump (HPGP) filter elements and critical seals
• Turbocharger bearing cartridge or complete rotor assembly
• Critical sensors and actuators for the ME-GI control system (e.g., FIVA valve position sensors, gas pressure sensors)

Safety

• **High-Pressure Gas Leaks:** LNG is stored and injected at very high pressures (up to 300 bar). Leaks pose severe fire and explosion risks. Ensure gas detection systems, ventilation, and quick-closing valves are fully functional.
• **Crankcase Explosions:** Accumulation of oil mist in the crankcase can lead to explosions. Verify oil mist detector (OMD) functionality and regular crankcase inspections.
• **Hot Surfaces & Exhaust Gases:** Engine components, especially exhaust piping and turbochargers, operate at extremely high temperatures. Exhaust gases are toxic. Ensure proper insulation and ventilation.
• **Rotating Machinery:** Guards for rotating parts (flywheel, turning gear, turbocharger) must be in place and secure during operation.
• **Confined Spaces:** Entry into scavenge spaces or crankcase requires strict adherence to confined space entry procedures, including gas freeing and ventilation.

Class survey

Class surveyors will focus heavily on the structural integrity, safety systems, and compliance with statutory regulations. Key checks include: **Crankcase Inspection:** Opening of crankcase doors for visual inspection of main and connecting rod bearings, crankshaft, and oil mist detector functionality. **Scavenge Space Inspection:** Checking for cleanliness, deposits, and fire flaps. **Fuel Gas System:** Verification of the integrity of the high-pressure gas piping, gas detection systems, ventilation, quick-closing valves, and emergency shutdown procedures. **Safety Devices:** Testing of overspeed trip, low lube oil pressure, high cooling water temperature, and other critical alarms/shutdowns. **Steering Gear & Emergency Systems:** While not directly engine-specific, the surveyor will verify the main engine's ability to support these critical systems. **Documentation:** Review of maintenance records, running hours, lube oil analysis reports, and performance data. **Operational Test:** Witnessing engine start-up, load changes, and potentially fuel changeover (HFO to LNG and vice-versa) to confirm proper operation and control system response.