BP goes oil free on tanker prop shaft bearings
Safer than safe. That sums up the design philosophy on four 185,000 dwt Alaskan-class tankers that will soon be carrying oil along the U.S. West Coast. Currently being built in San Diego by NASSCO, the BP Shipping-owned vessels feature the latest innovations in safe-ship design, including Thordon COMPAC water-lubricated propeller shaft bearings.
"When moving oil by sea," says Stan Taylor, Technical Manager for BP, "our philosophy everywhere in the world has always been on safety." In fact, it is an expressed business policy of BP to aim "to do no damage--to people, or to the environment."
During the design phase of the vessels, BP was determined to leave no option unexplored in its quest to minimize the risk of oil leakage. This included building in multiple redundant systems, and eliminating the use of oil wherever possible. "The prop shaft is an area where, traditionally, some lubricating oil can leak into the sea," says Taylor. "So we needed to look for alternatives."
Traditionally, propeller shaft bearings on commercial tankers are made of white metal lubricated by oil. Although these systems work well, keeping the oil and water separate can be a challenge. If seawater contaminates the bearing area, prop shaft performance can be compromised. If oil escapes into the sea, that's pollution. "Even a small leakage from the prop shaft," says Taylor, "can result in a visible sheen when in port."
This is one of several reasons that made Thordon's pollution-free alternative attractive.
The Thordon COMPAC propeller shaft bearing systems now being installed on each of the BP vessels feature water lubrication, no use of oil (and therefore zero risk of pollution), and an expected minimum 10-year bearing wear life based on systems currently in operation.
To ensure a steady supply of abrasive-free seawater to the bearings, Thordon also supplied its integrated Water Quality Package. This maintenance-free system includes pumps, flow alarms and a separator capable of eliminating particles down to 50 microns from the seawater lubricating the bearings.
"The Thordon system is the perfect choice for BP," says Taylor, "because its pollution-free characteristics are consistent with the design philosophy of the ships." The first vessel is due to launch in Spring 2004 and, because of a dedication to protecting the environment, these ships are set to carry oil by sea, safely, for decades to come.
Thordon Bearings Inc. is the leading supplier of high performance, environmentally friendly propeller shaft and rudder bearing systems to the global marine market. Thordon bearings are available worldwide through over 70 agents and distributors. The company is a member of the Thomson-Gordon Group, a third generation family-owned business founded in 1911.
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