Currently, the majority of ocean-going vessels operate on oil-lubricated bearings. Stern tube shaft seals are the only barrier between the oil and the sea, and over time, the seals can become damaged or worn allowing oil leakage to occur. Thordon Bearings (Burlington, Canada) has introduced TL3G, a water-based, biodegradable lubricant specifically developed to operate in Thor-Lube Stern Tube Bearing System. The system, consisting of TL3G lubricant, Thordon XL polymer bearings and a lubricant circulation and monitoring package, is an environmentally-friendly option to eliminate the pollution risk associated with oil filled stern tubes.

The issue of stern tube oil leakage is quickly moving from what was once considered normal “operational consumption” to being treated by global legislation as environmental pollution with full legal consequences. TL3G addresses this problem while providing ship owners and managers an alternative to oil lubricated stern tube systems. It has minimal environmental impact if leaked, due to its high water content and the rapid biodegradability of its low level of organic components. TL3G leaves no surface sheen as it is slightly heavier than water and highly soluble. Low friction levels are observed, not only at shaft start-up, but also through the entire shaft speed range as a result of TL3G’s friction reducing properties in combination with Thordon’ s XL polymer bearings. Viscosity is similar to an SAE 30 mineral oil in the system operating temperature range and has been formulated to promote rapid generation of a hydrodynamic fluid film.

Currently, Thordon has orders for seven Thor-Lube systems including new TL3G lubricant to be installed on LNG carriers being built at Daewoo and HHI of South Korea and MHI of Japan.