Thordon Bearings’ ThorPlas-Blue has established itself as the bearing of choice for deck equipment, with European shipyards and owners frequently specifying the grease-free bearing system as standard for vessels’ winches, fairleads, davits, capstans and windlasses, the company said in its release.
Sweden’s Falkvarv AB, Oresund Dry Docks, and the Oskarshamnsvarvet shipyard have been particularly strong proponents of the grease-free bearing, with these yards maintaining an inventory of ThorPlas-Blue stock with which to replace worn and costly bronze bearings and bushings when vessels drydock for repairs.
ThorPlas-Blue is a simple-to-machine-and-install self-lubricating bearing so does not require any lubricating grease. The economically and environmentally acceptable solution is especially pertinent to sensitive areas like the Baltic Sea.
Outside the Baltic area, Romania’s Constanta Shipyard has just completed the retrofit installation of ThorPlas-Blue bearings to deck winches and windlasses aboard a 105,042dwt Aframax tanker operated by a Greece-based ship manager.
This project followed a similar retrofit in July 2018 to a sistership at a Piraeus drydock, where anchor and mooring winch bearings were replaced with the Thordon solution.
The 105,459dwt tanker reported pieces of metal on deck and excessive bearing clearances in bronze rope drum bearings. The biggest clearances were recorded in the port and starboard anchor winches and the forward starboard mooring winch. Five shafts were dismantled and inspected, with excessive wear and corrosion recorded on the shaft journals, reaching up to 4.50mm (0.18 in) in diameter.
All in all, twelve bronze bushings were replaced with the self-lubricating ThorPlas-Blue bearing, each of which was machined to achieve 0.3mm (0.01in) final interference (running) and shrunk to fit housings using solid carbon dioxide (dry ice).
Minerva Marine is another Greek owner to frequently specify the Thordon technology. Since 2016, when ThorPlas-Blue replaced the greased bronze mooring winch bearing aboard the crude oil tanker Minerva Hellen, the owner has eliminated the costs and maintenance associated with the constant application of grease and has now installed the bearing on other assets.
The bearing can be machined and installed quickly into a variety of applications where greased bronze bearings are traditionally installed, including lifeboat and tender davit systems; fairleads, which can have a huge impact on mooring ropes that wear quickly; tiller arms and jockey bars; cranes and hoists; pivot point bushings; winches, capstans, water-tight doors and hatches. They can also be supplied as a Self-Aligning Bearing (SAB) for use in rudder and steering gear systems to counter the alignment problems typical of hydraulic steering systems.