7S90ME-GI10
The MAN 7S90ME-GI10 is a high‑power (≈90 MW) low‑speed 2‑stroke dual‑fuel engine that can run on HFO/VLSFO or LNG with instant fuel switching and near‑zero methane slip.
Engine Specifications
Inspector Detail
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Designation decoded
{'7': 'Number of cylinders: 7', 'S': 'Super-Long-Stroke ratio (S/B approx. 4.0)', '90': 'Bore: 900 mm', 'ME': 'Electronically controlled (MAN Electronic) two-stroke engine', 'GI': 'Gas Injection – high-pressure gas injection (approx. 300 bar, diesel cycle)', '10': 'Mark/Version 10'}
Background
The 7S90ME-GI10 is a Super-Long-Stroke engine with a 900 mm bore and 3260 mm stroke in the Mark 10 version. As one of the largest ME-GI engines in the portfolio, it is designed to power large LNG carriers and VLCCs. At 900 mm bore, individual components weigh over 6 tonnes, placing special demands on maintenance logistics and crane capacities.
Calculated metrics
Inspector checklist
- Check cylinder liners for scoring, cloverleafing and polishing
- Inspect piston rings for wear and fracture
- Check cylinder oil feed rate and BN value (BN25 in gas operation)
- At 900 mm bore: components >6 t – check lifting gear, dry dock required for piston withdrawal
- Inspect piston crown for burn marks and erosion
- Check gas injection valves for tightness and coking
- Inspect high-pressure gas lines and double-wall piping system for leaks
- Check gas pressures (280–320 bar)
- Test safety and quick-closing valves
- Check inert gas monitoring in the double-wall piping
- Check FIVA valves for function and response times
- Inspect HPS and HCU for leaks
- Read out EICU fault memory
- Test gas/diesel changeover
- Check turbocharger for bearing clearance, fouling and vibration
- Check scavenge air pressure and temperature
- Compare exhaust gas temperatures of all cylinders
- Inspect charge air cooler
- Check crosshead bearing for wear and lubrication
- Check stuffing box for gas blow-by and oil leakage
- At 900 mm bore: pay special attention to crosshead pin loading
- Check oil scraper rings
Logbook reference values
| Parameter | Expected | Deviation means |
|---|---|---|
| Gas injection pressure | 280–320 bar | Pressure below 280 bar: incomplete combustion; above 320 bar: mechanical overload |
| Exhaust gas temperature (gas operation) | 370–420 °C | Deviation >30 °C between cylinders: check gas distribution or GI valve |
| Exhaust gas temperature (diesel operation) | 340–410 °C | Increased temperature: check injection or timing |
| Pmax (firing pressure) | 155–185 bar | Deviation >5 bar between cylinders: check valves |
| Pilot fuel share | 3–8 % | Increased share: GI valve problems |
| Cylinder oil feed rate | 0.6–1.0 g/kWh (BN25) | Too low: wear; too high: deposits |
| Cylinder cooling water temperature | 75–85 °C | Below 75 °C: risk of cold corrosion in gas operation |
Common Failure Modes
Expert tips
- 💡 At 900 mm bore, pistons, liners and cylinder heads weigh >6 t – coordinate maintenance planning with shipyard stays and crane capacities. Piston withdrawals require a dry dock.
- 💡 Always use BN25 cylinder oil in gas operation and check the Alpha Lubricator setting for gas operation.
- 💡 Methane is lighter than air – install gas detectors at the highest points of the engine room and calibrate them regularly.
Related components
Classification & regulatory
['IMO Tier II worldwide; Tier III in ECAs – gas operation achieves Tier III without exhaust gas aftertreatment', 'IGC Code: requirements for gas systems', 'SOLAS Chapter II-2: fire protection for gas-fuelled ships', 'MARPOL Annex VI: SOx and NOx limits']
Reference content for inspector orientation. Always verify against manufacturer's manual, latest service letters and class society requirements.
Other Cylinder Configurations 36
Components & Design
Component data being added…
Technical Data
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