Thordon Bearings Inc


The new U.S. EPA Vessel General Permit (VGP) became effective in December 2013. The law stated that any vessels trading in US waters must use an EAL “Environmentally acceptable lubricant” in all oil to sea interfaces, such as the stern tube before their next drydocking. EPA also recommended that all new build vessel operators endeavor to use seawater-based systems for their stern tube lubrication to eliminate the discharge of oil from these interfaces to the aquatic environment.

In most cases, you cannot just replace the mineral oil with an EAL. Oil-based EALs need to be compatible with the sealing materials to ensure leakage is controlled – likely an upgrade to a new seal is required. Oil-based EALs may impact on the seal life which results in increased maintenance costs. Furthermore, oil-based EALs are typically over 7 times more expensive than the mineral oils used in oil-lubricated propeller shaftlines. It is not possible to guarantee that oil leakage to the ocean will never occur from the seal interface - fishing nets and ropes further add to the risk as they can become caught around the propeller shaft and cause damage to the seals. Any discharge of oil-based EALs requires that the ship owner report the discharge to the U.S. Coast Guard, and the owner is responsible for cleanup and disposal.

Fitted to over 2000 ships, Thordon COMPAC seawater lubricated propeller shaft bearing systems eliminate oil leakage from stern tubes, provide excellent operational and bearing wear performance comparable to oil lubricated metallic bearings, and lower in-service costs. COMPAC bearings eliminate the aft seal, as well as the storage, sampling and disposal of oil. Seawater lubricated bearings are recommended by the U.S. EPA and meet the new requirements of the pending Polar Code. The Thordon COMPAC Propeller Shaft Bearing System is guaranteed to meet Classification Society bearing wear specifications for 15 years for newbuildings or Thordon Bearings will supply new bearings free of charge.

One of the largest ship owners in the world, China’s COSCO, has ordered 20 COMPAC seawater-lubricated propeller shaft bearing systems for a 90,000dwt semi-submersible heavy transport vessel, three 50,000dwt semi-submersibles, four 36,000dwt bulk carriers, three 50,000dwt bulk carriers, two bulk carriers, four AHTS vessels, a 2D seismic vessel, a 28,000dwt heavy-lift ship and a 12,800dwt bitumen tanker. Other vessel types such as cruise ships, oil tankers, bulk carriers, container/dry cargo and ferries have installed COMPAC seawater lubricated propeller shaft systems. Matson Navigation of the U.S.A. has also ordered COMPAC for 2 of its 3600TEU container ships.

Recently, China Class Society, Lloyds Register and Bureau Veritas have modified rules for seawater lubricated propeller shaft systems, allowing the shaft to remain in place if monitoring conditions are met making COMPAC system comparable to oil lubricated propeller shaft bearings. Thordon’s COMPAC systems ensures shipowners/operators that there will be no environmental violations resulting from stern tube oil leakage and meets both U.S. VGP and Polar Code regulations guaranteeing zero risk of pollution.

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