Steve Bee, Group Marketing and Strategic Projects Director of marine fuels testing company VPS, on Monday (14 April) explored how Fuel System Check Monitoring can play a vital role in protecting a vessel’s engine as engine damage can be a very costly risk for vessel operators:
Statistically, data indicates that a vessel will suffer between one and two incidences of main engine damage over the course of its operational lifetime. The average damage costs have been estimated at around $650,000 per incident, with even more damaging incidents costing up to $1.2 million per claim. Therefore, it is important to identify the main causes of this damage and understand how it can be prevented.
Prevention of damage is, of course, preferable to cure. Fuel quality and handling issues remain a leading contributor to critical main engine failures. VPS frequently observe that such issues could have been prevented through the implementation of a robust and well-structured fuel management programme onboard vessels.
A common misconception is that a fuel meeting the international marine fuel quality standard, ISO 8217, means it is “fit for purpose”. But this is definitely not the case as even fuels that are “on specification”, at the point of delivery to the vessel, can cause major engine damage if not properly managed post-delivery. ISO 8217 specifies the requirements for petroleum fuels for use in marine diesel engines and boilers, prior to appropriate treatment before use, which means that fuels should then be treated onboard between delivery and being burnt
Catalysts used in petroleum refining are made of Aluminium Silicates, which over time breakdown. The resulting, coarse, dense fragments composing of aluminium and silicon, eventually reside in the residual portion of the refining stream. Known as “Cat-Fines”, these particles are highly abrasive and can cause severe damage to vessel engine parts.
Major marine engine manufacturers recommend a fuel should contain less than 10-15 mg/kg Aluminium plus Silicon (Al+Si) at the engine inlet. However, assuming a delivered fuel meets the stringent ISO8217:2024 limits of 40-60 mg/kg Al+Si, dependent upon the fuel grade, the fuel treatment plant would have to operate at an efficiency level capable of removing 75%-83% of these highly abrasive particles in order to meet the engine manufacturers’ requirements.
Furthermore, the International Council on Combustion Engines' (CIMAC’s) recommendation regarding fuel quality states “Fuel analysis is the only way to monitor the quality of fuel as delivered at the time and place of custody transfer, before and after the fuel cleaning onboard and at the engine inlet. Regular monitoring of the fuel cleaning plant will provide information, which will help to make decisions about the maintenance cycles of the equipment as well as potential engine problems resulting from malfunctioning or inadequate operation.”
Yet one of the most important, but often overlooked processes, is that of regular Fuel System Checks (FSCs) in order to assess the level of aluminium and silicon catalytic fines within fuel. The presence of “cat-fines” within fuel can be extremely damaging, causing rapid engine-part wear. Monitoring cat-fine levels before they can enter vessel engines, can prevent such damage. Therefore, sending samples for analysis which are taken Before & After purification processes, on a quarterly basis is the most effective way to monitor cat-fine levels. FSCs will also help comply to the engine manufacturers general recommendation of a maximum of 10-15 mg/Kg level of cat-fines in the fuel, entering the engines and assess purifier efficiency.
There are numerous reasons why regular fuel system checks are critical:
- Help identify potential risks & operational issues before major damage occurs.
- Confirm that the system’s flow rate, temperatures, discharge cycles are properly adjusted to handle the specific fuel that is being treated
- Verify that the fuel treatment system is properly maintained
- Reduce operating cost and increase lifecycles of critical components
- Identify presence of unusual components that can enter fuel post- delivery.
Periodic sampling from the fuel treatment system will also identify problems such as water ingress from ballast systems, leaking heating coils and cargo contamination. The last thing anyone wants to see is a purifier working as a pump!
A prime example and case study is highlighted below:
An LPG Tanker bunkered HSFO in Fujairah where its fuel met ISO 8217 specifications. However, after using the bunkered fuel, the Chief Engineer reported the main engine expansion tank low level alarm, with the main engine exhaust gas temperature high on cylinder unit 2 & 4. The vessel commenced a gradual slowdown of the main engine. The Chief Engineer reported the vessel was unable to run the engine due to suspected leaks on the main engine cylinders. The vessel drifted for about 10 hours before dropping anchor off the coast of India.
Upon dismantling the engine, the following findings were made:

The VPS Technical Advisor recommended the vessel submit fuel system samples and upon checking, the results from the system, these indicated that the purifier was in fact only working like a pump.

The screening size of Al+Si on the before engine sample further confirmed why the vessel was having problems, as the physical size of Al+Si particles ranged: 5-45 µm.

The ideal particle size range of cat-fines that can be effectively removed by a marine vessel's purifier system typically falls between 5 to 15 µm. Purifiers are designed to target these smaller particles, as they are the most common size found in heavy fuel oil and can cause significant wear and damage to engine components
If the particle size of catalytic fines is greater than 15 µm, it can pose significant risks to marine engines. Larger particles are more abrasive and can cause severe wear and damage to critical engine components such as cylinder liners, piston rings, and fuel injectors.
Note: The full article by VPS can be found here.
Photo credit: VPS
Published: 15 April, 2025