FOBAS Alert: Off-Spec Aluminium and Silicon (Cat Fines) Fuels in Singapore

In the last week FOBAS has tested a number of fuel samples bunkered in Singapore which have tested Aluminium and Silicon concentration (Al+Si) at levels above the 95% confidence limit of the respective ordered grades.

Results have ranged from 74mg/kg up to 97mg/kg. Al+Si at these levels would be difficult to reduce to acceptable levels during on-board treatment.

The usual maximum recommended level at engine entry is 15mg/kg, meaning that for fuels with Al & Si content at 97mg/kg, a minimum reduction of 85% would be required to reduce it down to the acceptable levels for engine entry.

Carry over of abrasive Al+Si material into the engine may lead to accelerated wear and damage to fuel pumps/injectors and cylinder components.

The following steps can be taken to maximize the Al+Si reduction:

• Fuel should remain in settling tanks for the maximum possible time, with elevated heating as appropriate, to facilitate gravitational separation of Al+Si through settling. Both settling and service tanks should be drained off at regular intervals.
• Separators should be operated using optimum arrangement and settings, ensuring optimal fuel flow rate and steady state fuel through-put temperature of 98 Deg C to enhance separator efficiency. The de-sludge cycle frequency may be increased to optimize bowl cleanliness and separation efficiency in removing Al+Si from the fuel oil.

Further recommendations for monitoring performance and signs of increased wear include:

• Attention should be given to any increase in fuel rack position needed to maintain set engine revolutions/load, which may indicate increased wear rates of fuel pump/injectors.
• Spot checks on ring packs and liners should be carried out at the earliest opportunity for signs of Al+Si abrasive wear.

In case that a vessel bunkers a fuel with a tested Al+Si off-spec as above the first action we would recommend is that further samples are taken from upper, middle, lower and bottom of the respective bunker storage tanks to confirm the original result and to establish the distribution of the Al+Si in the fuel.

Additionally, the suppliers should be contacted and requested to comment on the results.

As a good practice we would recommend regular checks of purifier performance by having samples taken from the inlet and outlet of all purifiers analysed for at least water, ash and element concentration, including Al+Si, to be confident of purifier performance at all times.

This service of "Purifier Monitoring" is available from FOBAS and any further pricing and procedural guidance is available from the contacts listed below.

If you require any further information about this Bulletin, please contact us at fobas@lr.org or speak to one of our consultants on +44 (0)330 414 1000 (Southampton UK), +44 (0)1642 440991 Redcar (UK), +65 3163 0888 (Singapore), +30 210 4580 932 (Greece).