Gard has recently seen several examples of engine breakdowns resulting from catalytic fines/sludge having accumulated in the tanks and entered the fuel system during operation.
International legislation requiring the use of fuels with a limited sulphur content has led to a steady increase in the levels of catalytic fines (cat fines) found in fuels. The current global average for low sulphur fuel (LSFO) is more than 30 ppm and this level increases the danger of cat fines settling and accumulating in the bunker and settling tanks. It also increases the risk that, in rolling conditions or rough weather, the fuel entering the purifiers contains cat fines in a concentration exceeding that which the purifiers are able to handle.
It appears that the majority of the fuel samples received and analysed by DNV Petroleum Services in 2013 were tested against the older ISO 8217:2005 marine fuel specification instead of the latest ISO 8217:2012 specification. The new specification introduced stricter requirements on several fuel parameters, and reduced the maximum permissible level of cat fines from 80 ppm to 60 ppm. Taking the unscheduled and costly engine breakdowns into consideration, we find it somewhat surprising that the majority of operators are still testing against the older ISO 8217:2005 specification.
There is, however, a discrepancy between the maximum acceptable levels of cat fines as stated in common marine fuel specifications such as the ISO 8217 and those recommended by engine manufacturers, which are typically 10-15 ppm. It is therefore important that the fuel treatment plant is managed and operated in the most efficient way in order to reduce the levels of bunker cat fines to less than 15 ppm at the engine inlet and hence prevent serious damage to main engine components. In this respect, The Joint Hull Committee of the London insurance market has issued guidelines on how to prevent engine damage due to cat fines. We summarise below the main recommendations made by the Committee in its report.
Prior to bunker fuel delivery
The agreed ppm value of aluminium (Al) andsilicon (Si) in charterparties and bunkering contracts should preferably be kept below 60 ppm (ISO 8217:2012) to ensure that the purifiers can effectively bring this value down to less than 15 ppm at the entry to the engines. It is recommended that the contractual agreement also considers the maximum density for the separators installed in the system (Conventional versus HD).
Note; if bunkered oil contains more than 60 ppm of catalytic fines as expressed by the Al and Si levels, in some instances fuel at the engine inlet has had higher levels of cat fines than those recommended, due to the limitations of on board fuel treatment equipment.
During and immediately after bunker fuel delivery
Ensure that representative bunker samples are drawn in line with industry guidelines and tested by a suitable independent laboratory, preferably against the ISO 8217:2012 specification requirements:
Note; in the unlikely event of an emergency where the bunker fuel has to be used without receipt of analysis results, contact the technical superintendent for permission.
During use of bunker fuel
Regular testing after bunker fuel purchase
Fuel storage, settling and service tanks
Crew and operator must maintain records of bunker fuel management procedures, including maintenance records and reports of mechanical or procedural failures.
If a problem is found
If engine damage is thought to be due to cat fines, experts should be instructed to confirm the presence of cat fines. Such confirmation can only be obtained by replica testing of the affected cylinder liners and piston rings carried out by the engine maker’s technicians.
If the presences of cat fines are confirmed, all tasks necessary to eradicate them from the fuel should be carried out immediately. This should include:
This will help to prevent the escalation of engine damage caused by cat fines, and minimise delays in commercial operations and unnecessary additional costs and insurance claims.
Options for improvement
Operators are recommended to carry out an internal review of their bunker handling and treatment procedures. They may also wish to enhance their planned maintenance by increasing inspections of engine cylinder assembly parts in order to provide early identification of fuel related problems. Apart from inadequate equipment it is the actual operation, or rather the improper operation, that may be the main reason for insufficient reduction in cat fines. Improper operation in turn may be due to lack of an understanding and the attitude towards proper on board fuel treatment.
 Joint Hull Committee (2013), «Marine Engine Damage due to Catalytic Fines in Fuel», London.