LOW SULPHUR FUELS EXPECTED TO CONTINUE TO CAUSE HEADACHES


A recent FOBAS report assessed the rise in combustion related incidents between November 2019 and June 2020.A recent FOBAS report assessed the rise in combustion related incidents between November 2019 and June 2020.



Analysis from Lloyd’s Register’s Fuel Oil Bunker Analysis and Advisory Service (FOBAS) indicates that the dramatic increase in combustion related incidents between November 2019 and June 2020 can not be linked to off-spec very low sulphur fuel oil (VLSFO).

In a bulletin published this month, FOBAS highlights that the number of reported incidents of cylinder component damage in large two-stroke engines almost doubled in the eight months to June 2020, compared to the same period a year prior. Ships switching to VLSFO were less likely to experience cold corrosion than has been experienced with high sulphur fuel oil (HSFO) due to the relatively lower concentrations of catfines present in the new fuels. Instead, adhesive wear where metal to metal contact results in micro-seizure and scuffing was reported.  

The suspected fuels were tested for standard ISO 8217 (table 2) parameters, and results were satisfactory. In fact, FOBAS data indicates an improvement of around 10% on various ignition parameters compared to HSFO, with the exception of a few samples from Santos and one from Houston.

“Considering the robustness of large two-stroke engines in burning fuels with varying ignition qualities and in view of CIMAC guidelines, it is not straight forward to link the fuel quality with the reported issues,” states FOBAS.

The information received from the ships was, in most cases, insufficient to draw conclusions considering the ISO 8217 analysis performed on the suspected fuel samples were mostly satisfactory. However, says FOBAS, experience points to four main issues:

1. Most commonly, FOBAS has found that hard coated piston rings were not being used on engines despite being advised by engine manufacturers.

2. In some cases, cylinder lube oil feed rate was either too high or too low, resulting in a loss of lubrication or deposit formation.

3. Cylinder lube oil choice was also a factor: regular use of BN 70 oils can lead to the formation of calcium deposits. (FOBAS notes industry suggestions that these oils show better dispersancy characteristics than BN 40 oils.)

4. A lack of engine maintenance or engine components operated close to their useful remaining life are more likely to report issues.

The number of problems has been declining since March as ship operations are adjusted to cater for VLSFO, but the industry’s sulphur compliance story doesn’t end there. After a May peak in off-spec MGO, Veritas Petroleum Services (VPS) is expecting another one now, and this time, fuel quality has been pinpointed as the issue.

In May, VPS documented 95 cases (2.8 percent) of MGO samples where flash point was below 60oC, contravening SOLAS requirements. As a result of reduced demand from land and air transport sectors globally due to the COVID-19 pandemic, associated fuel prices have declined, providing the commercial incentive to blend these lower flash point fuels into bunker fuels, says VPS.

The number of issues have been in decline since May, but VPS is expecting a jump in off-spec MGO again in September as land and aviation fuel prices are again low.

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