Switching to a cylinder oil with a high base number (BN) at a lower feed rate helped the operator of the JPO Tucana mitigate cold corrosion while reducing feed rates by 45 per cent. The operator of container vessel JPO Tucana was concerned about the impact of cold corrosion on the vessel’s Wärtsilä 7RT-flex96C engine. Signs of cold corrosion had been found during a routine engine inspection, prompting the replacement of all piston rings and an increase in cylinder oil feed rates in order to safeguard against future damage. At this time the JPO Tucana was running an industry standard 70 BN oil.
To address cold corrosion concerns, ExxonMobil engineers trialled Mobilgard™ 5100, a 100 BN cylinder oil designed to optimise the performance of two-stroke marine diesel engines operating on heavy fuel oil (HFO) with a high sulphur content and protect them against cold corrosion. During field trials the JPO Tucana operated at engine loads of between 30 to 48 per cent maximum continuous rating using HFO with sulphur levels of between 2.5 and 2.81 per cent. Pistons 1 to 5 were lubricated with Mobilgard™ 5100 while units 6 and 7 used the 70 BN cylinder oil.
The tests showed minimal wear on cylinder liners and piston rings across all units. However, to obtain this result, the pistons using the 70 BN oil required a cylinder oil feed rate of 1.1g/kWh. For the pistons lubricated with Mobilgard™ 5100 the feed rate was as low as 0.65g/kWh, a 45% reduction in lubricant consumption.
Find out how we can help optimise your vessel’s performance and reliability by contacting an ExxonMobil representative.
This case study is based on the experience of a single customer. Actual results can vary depending upon the type of equipment used and its maintenance, operating conditions and environment, and any prior lubricant used.