...the need to avoid marine species being exposed to oil pollution make the choice of lubricants much more critical than in other shipping operations.
Triglycerides have poor low- and high-temperature performance so are not good from an engineering perspective. Polyglycols have a good low temperature operating characteristic but there are questions about their toxicity, and there have been cases of metal corrosion due to their hygroscopy.
Oils based on polyalphaolefin (PAO) require viscosity improvers to provide higher viscosity lubricants such as gear oil but VI additives can be broken down under conditions of shear, which reduces their viscosity and compromises equipment performance and life. Regular monitoring is required to replace PAO oil when its viscosity drops.
This leaves esters. Unsaturated esters are susceptible to thermal oxidation, resulting in polymerisation and an increase in viscosity. Under thermal stress a lubricant can go into a piece of machinery as an oil and turn into a grease! Again, regular viscosity monitoring is required.
Top-tier saturated ester-based lubricants, on the other hand, such as those marketed by independent Swiss lubricant manufacturer Panolin, exhibit very good thermal oxidation resistance and shear stability, and meet all the current environmental requirements. Panolin products carry ISO 9001 and ISO 14001 certification. Some also are approved by ABS.
Stocking the right lubricants from the outset is the right approach, and will of course minimise the environmental impact should there be a continuous loss of oil from a vessel’s lubrication systems. Panolin's lubricants have been designed with Solas and pollution prevention firmly in mind. That is an all-important consideration for any operator transiting polar routes.
Source: Riviera Maritime Jan 2017
Author: Phil Cumberlidge, business development manager PANOLIN GREENMARINE