Fuel supplier issues guidelines for operators

17 Feb 2014
ExxonMobil recommends sending fuel samples to an approved laboratory for analysis

ExxonMobil recommends sending fuel samples to an approved laboratory for analysis

ExxonMobil Marine Fuels & Lubricants has released what it refers to as ‘top-tips’ to help vessel owners and operators achieve good value when purchasing marine bunkers.

The company says that these considerations are particularly important given that marine fuel typically accounts for the majority of total ship operating cost. It advises operators to consider the following five key fuel quality factors:

ISO 8217:2012 permitted water content compliance level is 0.5%, while ExxonMobil’s marine fuel is claimed to have an average of 0.12%. If marine fuel is supplied at the 0.5% compliance level this could potentially cost US$6,000 per purchase for a 2,000t stem, and the water should be removed prior to burning. Water removed from marine fuel prior to use may then add a further disposal cost of up to US$3,000, the company says, plus additional maintenance costs may be incurred to remove resulting sludge from the purification systems.

Aluminium and silicon in marine fuels, known as catalytic fines, have the potential to cause significant engine damage, leading to substantial repair costs and potential vessel delays. ISO 8217:2012 and ISO 8217:2005 allow for levels of catalytic fines up to 60mg/kg and 80mg/kg respectively. ExxonMobil says that major engine builders typically recommend the level of catalytic fines should be less than 15mg/kg at the engine inlet. Its fuels are said to have significantly lower levels of catalytic fines, with an average of 10mg/kg, levels which help limit catalytic fine removal efforts, reduce abrasive wear on critical engine components and potentially avoid the cost of additional maintenance and possible breakdowns.

To help meet the lower sulphur levels specified in changing marine industry regulations, there may be a tendency to blend marine fuel from a variety of different sources which may cause the resultant blend to become incompatible. The company says that unstable fuels have the potential to cause sludge or heavy deposits to build up which may prove costly to resolve and may impede vessel performance. Its fuels arrive from an integrated supply chain and are said to be tested to strict standards before they leave the refinery or terminal, with systematic quality control throughout the supply chain.

Calculated Carbon Aromaticity Index (CCAI) level is the indicator of marine fuel combustion quality. It is, says the company, important that this is neither too high nor too low. Poor quality marine fuel with an inappropriate CCAI level, caused by incompatible blend components, could cause poor combustion, and it is said to potentially impact vessel performance. ISO 8217:2012 states a maximum of 870 for most common residual marine fuel grades and ExxonMobil’s marine fuels are claimed to sit within the working parameters of major engine manufacturers, helping to protect against poor performance.

Finally, ExxonMobil recommends that it is best practice to send fuel samples to an approved laboratory for analysis. This allows operators to understand the quality of the marine fuel received and how to manage the marine fuel system on board their vessels.

Links to related companies and recent articles ...