Cylinder lubricants and low sulphur fuels

SOx Emission Control Areas (SECAs)—see under the section on Fuels given above—impact on cylinder lubrication in low speed engines since the fuel dictated to meet emission controls is generally limited to a maximum 1.5 per cent sulphur content. Concern that contemporary cylinder oils (whether 70 BN or lower) might not be the best choice for service with low sulphur fuels was addressed by MAN B&W Diesel and BP Marine in answering these questions:

Should a newbuilding be specified with a dual storage and piping system for cylinder oils?

Shipowners are advised to seriously consider future operational flexibility for switching in and out of low sulphur fuel. To facilitate optimization in various scenarios it is sensible to plan ships with dual (or multiple) storage tanks to allow more than one cylinder oil grade to be carried.

Signal for lubrication from Capacitive feedback c0ntr0l unit

Signal for lubrication from Capacitive feedback c0ntr0l unit

Cylinder Setup
Figure 4.7 Alpha cylinder lubricator unit (MAN B&W Diesel)

The actual tank capacities may be open to debate but it is useful to start allowing for segregation.

What should be done when changing over to low sulphur fuel for short durations on random bunkers?

If regular inspection shows that 70 BN oil is performing satisfactorily, then consider remaining on that lubricant; as a caution, however, avoid running-in on low sulphur fuel with 70 BN oil, if possible.

What should be done when switching regularly between low and high sulphur fuels on a routine trading route ?

As above, but if there are two grades of cylinder oil onboard (70 BN and a suitable lower BN grade) then switch accordingly if that is convenient and if monitoring confirms that yields the best results. This could be the policy when SECAs become widespread.

What should be done when on prolonged operation with low sulphur fuel? Run on low BN oil and closely monitor to ensure it gives the best results.

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