MAN B&W L58/64 Cylinder Head (L58/64CD)

MAN B&W L58/64 & L58/64CD Cylinder Head (IMO-0690)

The MAN B&W L58/64 and L58/64CD cylinder heads are heavy-duty, bore-cooled cylinder covers engineered for medium-speed, four-stroke marine propulsion engines and heavy-fuel stationary diesel generators. Designed to operate reliably under extreme peak firing pressures and high thermal gradients, each unit features an optimized bottom plate design with drillings for high-velocity cooling water circulation, preventing low-cycle thermal fatigue and mechanical stress cracking.

Each cylinder head assembly accommodates two inlet valves, two exhaust valves with water-cooled valve seat cages, a centrally mounted high-pressure fuel injection valve, starting air valve, safety relief valve, and indicator cock bore.

Technical Specifications: 

Key Features

1. Bore-Cooled Flame Face: Drilled coolant galleries target heat away from the valve bridge zones, preventing high-temperature gas corrosion and mechanical cracking.
2. Exchangeable Water-Cooled Valve Cages: Exhaust valves sit in dedicated cooled cages, reducing valve seat operating temperatures during Continuous Heavy Fuel Oil (HFO) operation.
3. Optimized Port Aerodynamics: Flow-profiled intake and exhaust tracts minimize gas exchange pumping losses, improving scavenging and turbocharger efficiency.
4. High-Integrity Fire Deck Sealing: Precision-machined contact lands ensure gas-tight seating against the cylinder liner top face without premature blow-by.
5. Symmetrical Mechanical Load Distribution: Engineered multi-stud fastening perimeter eliminates uneven deformation during high-pressure hydraulic tightening.

Applications

• Commercial Marine Propulsion: Main prime mover for ocean-going container feeder vessels, bulk carriers, chemical tankers, and Ro-Ro freight vessels.
• Cruise & Passenger Vessels: Low-vibration, high-reliability propulsion machinery installations.
• Offshore Energy Operations: Power supply for deep-water drillships, heavy construction vessels, and offshore semi-submersibles.
• Stationary Power Generation: Heavy-fuel power plants operating in baseload and grid-stabilization capacities.

Compatible Equipment Models

Designed for all in-line configurations of the MAN B&W 58/64 series:

• MAN B&W 6L58/64 & 6L58/64CD (8,340 kW – 8,400 kW)
• MAN B&W 7L58/64 & 7L58/64CD (9,730 kW – 9,800 kW)
• MAN B&W 8L58/64 & 8L58/64CD (11,120 kW – 11,200 kW)
• MAN B&W 9L58/64 & 9L58/64CD (12,510 kW – 12,600 kW)

Part Numbers, MPN & Cross-References

• Manufacturer Part Number (MPN): IMO-0690 / Cat. No. 055.04.001
• Drawing / Plate Catalog Reference: 055.00 / 055.04 / 58/64 Series Sub-Assembly
• IACS Reference: IMO Tier I / Tier II Compliant Component Standards (NOx Technical Code)

Marine Chief Engineer’s Guide

1) Fire-Deck Sealing Land Inspection

Before landing the cylinder cover onto the cylinder liner, perform a clean-metal contact check using Engineer’s Blue. The sealing land must demonstrate a minimum of 80% continuous circumference contact to prevent high-pressure gas bypass and flame erosion. Always replace the joint ring (fire seal ring) with an OEM-spec soft iron/copper gasket.

2) Hydraulic Jacking Protocol

Follow the exact diagonal cross-tightening sequence prescribed by MAN Energy Solutions. Tension all cylinder cover studs uniformly in three defined stages (e.g., 30%, 70%, and 100% of final hydraulic pressure). Uneven tightening will distort the cylinder liner upper collar, leading to piston ring scuffing and blow-by.

3) Cooling Water Passage Cleanliness

When swapping heads, inspect the intermediate water transition pipes and O-rings. Ensure internal passages are free of scale deposits or calcium precipitation; even a 1 mm scale accumulation on the bore drillings can increase local flame plate temperatures by up to 80°C, risking thermal cracking between the exhaust valve bridges.

Frequently Asked Questions

What is the difference between the standard MAN B&W L58/64 and the L58/64CD cylinder head?

The L58/64CD variant incorporates updated compact-design modifications, including internal coolant flow improvements and revised valve pocket geometry to enhance thermal handling under continuous high-load HFO combustion. Ensure your engine’s build execution suffix matches when ordering replacement assemblies.

What is the standard overhaul interval for exhaust valve seats on this cylinder head?

When operating on standard heavy fuel oil (HFO) compliant with ISO 8217, exhaust valve cages and spindles should be inspected and serviced every 6,000 to 8,000 running hours. The cylinder cover main body should undergo full decarbonization, NDT crack testing, and cooling water passage descaling at major overhaul intervals (typically 24,000 to 32,000 hours).

Can this cylinder head be supplied fully assembled with valves and springs?

Yes. Units can be supplied as a bare casting (with valve guides and seats only) or fully dressed, including inlet and exhaust valves with springs, rotators, water-cooled exhaust cages, fuel injector pocket sleeves, starting air valves, and relief valves, calibrated and ready for immediate drop-in installation.

How is internal crack detection verified on reconditioned cylinder covers?

Every reconditioned cylinder cover undergoes two-stage Non-Destructive Testing (NDT). First, a high-sensitivity fluorescent Magnetic Particle Inspection (MPI) is conducted across the high-stress valve bridges and fuel injection bore on the fire deck. Second, a prolonged hydrostatic test at elevated pressure and temperature is conducted to verify internal casting partition walls between gas passages and cooling jackets.