Biodegradable oils for the Marine Industry – and how to select the most appropriate for your vessels

However you call them – biodegradable oils, bio oils, green lubricants, environmentally considerate, environmentally friendly or environmentally 'acceptable' lubricants (EALs), they are increasing significantly in their use, particularly where water is close-by.

PANOLIN engineer long life biodegradable lubricants that can last the lifetime of the vessel, or even just to provide effective medium term lubricant life, at lower initial cost outlay, for equipment that does not require/benefit from fill-for-life lubricant. With a heritage of more than 70 years of successful Swiss Oil Technology and having had a focus on high performance bio hydraulic oils and minimal toxicity lubricants for the past 35+ years, PANOLIN today is a global leader in EALs for the marine and offshore sectors.

PANOLIN's GREENMARINE biodegradable oil product range covers five types of lubricants, that include hydraulic fluids for propulsion systems, deck equipment and control lines; gear oils for gearboxes, thrusters and fin stabilisers; stern tube oil; greases and wire rope lubricant. They are used across all merchant vessel types, pipe/cable layers, dredgers and ROVs for applications in propulsion / steering / stability and also deck/platform machinery.

High performance, environmentally compliant, biodegradable lubricants for the Marine, Dredging and Offshore industries

From an environmental perspective, the US Environmental Protection Agency (EPA) led the way in their Vessel General Permit (VGP) requiring that EALs must be used in 'oil-to-sea interfaces and classing 3 lubricant types as meeting 'biodegradability' requirements:

• Triglycerides (HETG, a natural ester, otherwise known as Vegetable oil)
• Polyalkylene Glycol (HEPG, otherwise known as PAG, or Polyglycol) and....
• Synthetic Esters (HEES) - two classes: fully Saturated Esters and Unsaturated Esters

Polyalphaolefins (HEPR, otherwise known as PAOs, Synthetic Hydrocarbons, or 'man-made' mineral oils), are not included in the EPA list of Biodegradable Base Oils in their Environmentally Acceptable Lubricants document EPA 800-R-11-002 Section 2, of Nov 2011, or in their Presentation "Overview of the Final 2013 VGP" of Nov 6th 2013, as they are only biodegradable in low viscosities.

Note that some biodegradable oils are not solely made from one base oil type; they can be 'blends' of PAO and ester (typically unsaturated), to combine minimum performance and give the minimum requirement for biodegradability, or they can be a mix of Saturated Ester to provide performance requirements and Unsaturated Ester to reduce cost - the lower performing Unsaturated Ester being lower cost than the robust Saturated Ester.

However, from a performance point of view, to ensure reliable and safe operation of a vessel at sea the lower performing base oils are just not fit for purpose – especially where water or temperature are involved. Many issues are being reported of poor performance of biodegradable sterntube oils in equipment where previously mineral oils had proven to work - and particularly with instances of short life of stern tube lubricants (in some instances only 2 ~ 2 ½ years), before acidity of the lubricant increases, viscosity dramatically increasing, or the stern tube is contaminated with stinking black sludge that blocks seal oil-feed pipes and bearing oil lubrication grooves.

Other, more serious issues such as: corrosion of equipment internals due to the hygroscopic nature of the lubricant; overheating of seals, due to increasing lubricant viscosity/viscous shear and bearing wear in propulsion systems, questioning oil film thickness and frictional characteristics, are occurring.

PANOLIN's long-life saturated synthetic esters are leading the way in reliable, high performance and long-life marine biodegradable hydraulic oil and stern tube oil that are all US EPA VGP compliant, for all vessel application lubrication requirements - with availability around the world.

It is the lubricant manufacturer's job to tell ship Owners all about the key performance indicators of their biodegradable lubricant(s) – consult them and ask them what problems they have had occur with their EALs. The awkward body language and evasive answers of some EAL makers/suppliers will be amusing.