High density,high abrasive and high CCAI fuels in the gulf of Guinea
DNV Petroleum Services has tested four fuel oil samples delivered off the coast of Benin, Ghana and Ivory Coast, representing HFO delivered between 22 May and 30 May 2011 with density above the ISO 8217:2005/2010 maximum limits.
The tested densities were in the range of 1010.0 to 1015.4 kg/m while the density stated on the corresponding Bunker Delivery Notes was 991.0 kg/m. The bunkers came from one supplier and involved two bunker tankers.
The measured viscosity varied between approximately 270 cSt and 280 cSt at 50ºC with a corresponding CCAI (Calculated Carbon Aromaticity Index) value of 874 to 880, exceeding the ISO 8217:2010 maximum limit for RMG and RMK category fuels. Fuel Ignition and Combustion Analysis, using the FIA 100/FCA instrument on two of these samples, confirmed that these fuels exhibit poor ignition and combustion quality. The ECN (Estimated Cetane Number) of both fuels was around 13.
It is expected that medium and high speed diesel engines and in general engines of older design may not operate satisfactorily on a fuel oil in this condition,in particular at low load.
The Al+Si levels of these samples ranged from 90 mg/kg to 103 mg/kg as determined by ISO 10478, exceeding the ISO 8217:2005/2010 maximum limits. Al+Si at the levels tested indicate that the fuels contained elevated amounts of abrasive particles that could cause accelerated wear of diesel engine components, such as piston rings, cylinder liners and fuel pumps if not reduced sufficiently.
Due to the high density of these fuels, efficient centrifuging may be difficult to achieve. If such fuels nevertheless are used it is recommended to take samples before and after the fuel treatment plant to determine the expected fuel oil quality at the engine inlet,which will help in any subsequent assessment of increased engine wear and damages, and which may be important in resolving disputes.
This Bunker Alert does not necessarily reflect the overall fuel quality supplied in the subject area, but if your ship recently bunkered at this area or intends to do so, please ensure the fuel quality is known before use. DNVPS laboratories and regional offices span all time zones and can assist you with further commercial, legal and technical advice, if required.
Source: DNVPS