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According to information from Akasaka Diesel and recommendations from several other diesel manufacturers, excessive wear on piston rings and cylinder liners has recently been observed due to fuel oil containing catalytic particles used in fuel refining (hereinafter referred to as FCC fuel oil). Therefore, please pay attention to the following for your safe journey.
Several serious incidents have been reported from some vessels, such as combustion gas leaks from the combustion chamber due to excessive wear on piston rings and liners, excessive wear on high-pressure pumps, and problems at the fuel injector contact surfaces.
Please avoid using FCC fuel oil. It will severely damage the operation of the main engine, the service life of the ship, and operating costs if fuel oil containing FCC is used continuously.
When FCC fuel oil is received, appropriate pre-treatment with the ship’s fuel oil cleaning system must be carried out to prevent FCC from entering the engine.
1. Properties of FCC Fuel Oil
Generally, the catalytic particles in FCC fuel oil are almost spherical, ranging in size from 5 µm to 150 µm, and their main component is a compound of Aluminum and Silicon (this composition will be determined when analyzing LSFO oil samples by a specialized unit). It is as hard as abrasive material and very hard compared to steel.
If hard FCC particles penetrate the working surface between the piston and cylinder liner, this surface will be scratched. This hinders the formation of a normal oil film and causes scratching and gas leakage. Ultimately, this will cause rapid/excessive wear of the piston, piston rings, and cylinder liners.
FCC particles also damage the sliding surfaces or valve seats of high-pressure pump pistons and injectors.
Furthermore, although fuels containing components such as ash, aluminum, silicon, calcium, vanadium, phosphorus, and zinc are still recommended, exceeding the permissible limits of these components when entering the engine will increase mechanical wear and high-temperature corrosion. These unburned compound particles will collide violently with the nozzle and turbine blades in the exhaust gas stream, causing wear and tear, leading to component damage, and eventually causing the turbine to operate erratically and resulting in turbine “hopping.” These compound particles also pass through the exhaust valve system and the combustion chamber of the boiler, increasing mechanical wear and high-temperature corrosion, eventually damaging these components.
When FCC particles enter the stuffing box, it not only damages the working surface and exacerbates wear but also increases the amount of oil leaking from the piston seal.
2. If fuel containing FCC must still be used due to force majeure, please ensure the following points are observed to minimize damage to the main engine and boiler system.
Note that when the machine stops, the technical condition of the piston rings and cylinder liners should be regularly checked and observed.
2.1) Increase the amount of lubricating oil supplied to the cylinders compared to the level when using normal fuel.
2.2) Adjust the cylinder coolant temperature from 85°C down to 75°C to preserve/maintain the lubricating oil film.
2.3) Lower the temperature of the supercharged air entering the engine as much as possible.
2.4) Ensure that all sludge in the settling tank and the service tank is completely drained (at least several times a day). If the service tank has two suction inlets, one “high” and one “low”, use the “high” suction inlet.
2.5) Operating two fuel filters in parallel is best and improves sludge removal efficiency by minimizing the flow rate of fuel through the filters. It is recommended to maintain the fuel inlet temperature at 98°C to increase filtration efficiency and reduce catalytic fines (Al & Si…) to within acceptable limits before supplying the filter (according to Akasaka, the Al + Si content should be £10 mg/kg at the engine inlet).
2.6) DO NOT skip the fine filter during bypass operation.
2.7) If a cylinder liner temperature monitoring system is installed, monitor the system during engine operation.
3. Precautions in Fuel Receiving Procedures:
3.1- Only receive new LSFO fuel into empty tanks (do not mix two types of LSFO fuel from different sources as this will create sludge and damage filters, overloading fuel processing equipment).
3.2- The received fuel must comply with the technical specifications and limits according to ISO 8217:2017 standard. Before receiving fuel, request the supplier to send the vessel a fuel batch characteristic. It is best if the characteristic includes the (Al + Si) group analysis parameter mg/kg for consideration.
3.3- Fuel samples must be taken at the fuel receiving nozzle in the form of a drip and taken throughout the Bunker receiving process. Calculate the number of sample bottles as required during the Bunker receiving process (the vessel must retain at least 3 bottles), noting the seal numbers… and sign for confirmation. 3.4- Fuel samples must be handed over to the Distributor for onshore transport (photograph the seals), in coordination with the Ship Supervisor, to transfer the sample bottles.
3.4- Fuel samples must be handed over to the Distributor for onshore transport (photograph the seals), in coordination with the Ship Supervisor, to transfer the sample bottles.