Regulatory compliance was the focus of Marine Propulsion & Auxiliary Machinery readers attention in 2018. Craig Jallal, tankers and markets editor, looks back at the top five most-read stories.
Why are some stern tube lubricants failing?
The most-read story in Marine Propulsion & Auxiliary Machinery in 2018 was one from the final month of the year. Panolin business development manager Phil Cumberlidge took a long hard look at the subject of stern tube lubricants and in particularly environmentally acceptable lubricants (EALs).
The premise of the article was the difference in performance of synthetic (highly refined) mineral oils versus conventional mineral-based (petroleum) oils with attention paid to compliance with the US Environmental Protection Agency (EPA) and its vessel general permit. This requires that vessels entering US waters must use EALs in oil-to-sea interfaces.
The crux of the matter was the reported breakdown in performance in some synthetic lubricants and the resulting non-compliance to EPA standards, according to Mr Cumberlidge. It would appear that the working life of the synthetic EALs was, in some cases, shorter than the traditional variants. This should become evident from a DNV GL joint development project with several marine insurers and the University of Sheffield, which will investigate the increase in stern tube bearing failure.
There can, of course, be many reasons for stern tube bearing failure and on choosing lubricants, Mr Cumberlidge offered this advice: It is the lubricant manufacturer's job to tell customers about the key performance indicators of their lubricant(s) – so consult them and ask them what specific EAL base oil technology they use. If they say, "We use ester technology", ask if it is natural, unsaturated, or a blend of saturated and unsaturated ester, or if it is the 'real thing' – a fully 100% saturated synthetic ester.
Source: Marine Propulsion & Auxiliary Machinery, 24 December 2018
Author: Craig Jallal, tankers and markets editor