A Lloyd’s Register Fuel Oil Bunker Analysis Service (FOBAS) investigation has shown that the timing of an ’upsurge’ in reports of cylinder liner damage in large, two-stroke engines correlates with the shipping industry’s transition from high- to low-sulphur fuels
In an advisory bulletin, FOBAS presented data indicating that cylinder component damage incidents jumped from 14 to 30 comparing the same eight-month timeframe between November and June in 2018-19 and 2019-20.
By comparison, sludging incidents rose only marginally and fuel injection equipment failure incidents fell by nearly half.
In its report, FOBAS said it was asked to investigate the incidents to try to determine whether very low sulphur fuel oil (VLSFO) quality was a contributing factor to engine component incidents and failures.
FOBAS said its data indicated an average 10% improvement on VLSFO ignition parameters over high sulphur fuel oil (HSFO). This data also included one instance of poor ignition quality in a fuel oil sample from Houston, Texas in the US that was classed as an exception to otherwise better quality fuel from the port. Another instance in a fuel sample from Santos, Brazil, the advisory service suggested, extended a trend of low estimated cetane number samples from the location.
Still, the two samples were not enough to generalise, FOBAS said.
"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," said the report.
Similarly, FOBAS said they could not draw conclusions based on reports from ship incidents.
"The information received from the ships in most cases were insufficient to draw conclusions considering (ISO 8217) analysis performed on the suspect fuel samples were mostly satisfactory," FOBAS said.
Moreover, FOBAS said such incidents appeared to be declining as operators made adjustments for handling VLSFOs.
"Frequency of such incidents are on the decline with ships making necessary operational adjustments and getting more experience of burning VLSFO in their engines."
Ultimately, FOBAS suggested owners, operators and technicians seek support from OEMs on best practices and use condition-based monitoring tools to prevent failures.
"In cases such as damage to cylinder liner and piston rings, it is important to seek guidance from the engine manufacturers. Moreover, ship operators should refer to their engine operations manual, consult the latest service letters and also apply a best practice approach to mitigate and avoid future occurrences. In light of varying fuel quality VLSFOs, the use of appropriate condition monitoring tools could further reduce the risk of breakdown scenario through diagnostic capability of picking up any incipient failure," FOBAS said.
The full report can be found here.