Refinery catalytic fines in marine fuel oil are not a new problem but in recent years there appears to have been an increase in the frequency of engine damage caused by these highly abrasive particles, UK P&I Club advised in an article written by Brookes Bell.
As explained, refineries use catalysts to improve the yield of high value products, such as gasoline, refined from crude oil. Unfortunately, some of these fine particles escape into side stream products that are used as blend components in the production of residual grades of marine fuel. This particulate matter, comprising of aluminium and silicon oxides, is extremely hard and, if entrained in the fuel as it enters engines, can cause severe abrasive wear.
In response, the Club published technical advise for operators, to minimize risk by incorporating the following into management systems:
- Insist on a maximum combined level of aluminium and silicon in fuel deliveries of 60mg/kg. (ISO 8217:2010 or later versions).This may be incorporated into a time charter party or an order direct with a bunker supplier.
- Sample and test all deliveries. Ensure a representative bulk drip sample is taken throughout each delivery and that this bulk sample is thoroughly mixed before pouring into sub-sample bottle.
- Always operate separators with minimum acceptable flow rate (with consideration to consumption) and with a fuel inlet temperature of 98˚C.
- As general guidance, take samples before and after the separators each time the delivery sample analysis shows combined aluminium and silicon above 40mg/kg.
- Review and adhere to the autobackflush filter manufacturer’s operating instructions, ensuring shipboard operational procedures cover such requirements.
- Manually clean and thoroughly inspect the condition of all fuel filters on a regular basis,and when high differential pressures are observed or auto-backflush periods start to increase.
- Ensure a complete set of spare filter elements is available on board at all times.
- Regularly ‘dewater/desludge’ settling and service tanks.
- Routinely open and clean the bottom of settling tanks and service tanks (possibly to coincide with interim/special surveys,for example).
- Routinely open and clean the bottom of primary storage tanks (possibly to coincide with special surveys, for example).
- As well as regular scavenge/underpiston space inspections take main engine cylinder oil scrape down samples every two months and send for analyses.
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