Slow steaming has become standard for many operators. Technical issues connected with slow steaming, with particular reference to:

In slow steaming, especially when a turbocharger is cut out (on multi-turbocharger engines) to keep the remaining turbocharger in its efficient range, the engine runs at low load with reduced charge air pressure. The crosshead bearing (which connects the connecting rod to the crosshead) operates with an oscillating motion and relies on a hydrodynamic oil film. At low load/speed, the oil film may be thinner and the bearing load pattern changes; the reduced speed and the altered firing can cause the crosshead bearing to run with boundary lubrication, leading to wiping, overheating and damage. Also, with a turbocharger cut out, the engine load distribution and the combustion may be uneven, increasing the load on some bearings. The crosshead bearing is particularly at risk because it cannot build a full hydrodynamic film (oscillating motion) and depends on the oil being forced into the bearing. Slow steaming with T/C cutout can therefore cause crosshead bearing damage (wiping, fatigue) if the load and lubrication are not managed.

At low load (slow steaming), the cylinder liner wall temperature falls. If the liner temperature falls below the dew point of the sulphuric acid formed from the fuel sulphur and combustion water, the acid condenses on the liner, causing "cold corrosion" - corrosion wear of the liner and rings. This is aggravated by the low load because the heat input is low and the liner is not kept hot. The corrosion removes material from the liner, increasing wear and reducing the liner life. It is prevented by keeping the liner temperature up (insulating the scavenge space, raising the jacket water temperature), by using a cylinder oil with adequate BN to neutralise the acid, and by matching the oil feed rate to the load. If the fuel is low-sulphur, the corrosion is less, but the risk remains if the liner is cold.

At low load, the exhaust valve operates at a lower temperature and with less gas flow. This can cause:

1. Carbon and deposit build-up on the valve and seat (from incomplete combustion at low load), leading to poor seating, blow-by, and burning of the valve.
2. Cold corrosion of the valve seat (acid condensation) causing pitting and wear.
3. The valve may not rotate properly (if the rotation depends on gas flow), leading to localised wear and burning.
4. Thermal stress from the temperature cycling.

These cause the exhaust valve to leak, overheat, and eventually fail (burning, cracking). Prevention: keep the valve clean, ensure proper rotation, maintain the combustion quality, and periodically run at higher load to burn off deposits.