SL2017-638/DOJA Cleaning of Heavy Fuel Oil and Maximum 0.10% Sulphur Fuels

This Service Letter specifies the recommended maximum acceptable level of cat fines entering the engine, which is as follows:
ƒAlways keep the level as low as possible and, max. at 15 ppm
Al + Si at engine inlet for short periods.
Some guidelines on optimal operation are also given:

Remove the cat fines from the fuel by setting a high temperature (min. 98°C) and a low flow in the fuel separators.
ƒ
Enable proper cleaning of the tanks in service by making the overflow pipe in the service tank go to the bottom of the tank, and/or
by using a separate line to recirculate the fuel to the settling tank.
ƒ
To be warned when the fuel system is not operating optimally, a 10 μm abs. fine-filter should be installed in front of the engine.

Summary
Cat fines are small, very hard particles found in marine fuel. Cat fines can wear the engine down very fast, and they must be removed from the fuel by the fuel cleaning system on board the ship.