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BP fixing design flaw in new tankers
BP has identified and is repairing the design flaw which caused rudders to crack in its new double-hulled Alaska-trade tankers.
One of the ships, the Alaskan Frontier, has already been repaired; a second tanker, the Alaskan Explorer, is in for repair; and the two tankers still under construction have been inspected and had remedial work done, BP Exploration (Alaska) spokesman Daren Beaudo told Petroleum News in mid-July. The work involved correcting a manufacturing issue, he said.
The problem was identified during a combined U.S. Coast Guard critical area inspection and warranty inspection done on the Alaskan Frontier, which entered service Aug. 21, 2004. Inspectors discovered the problem May 15, during a 20-day inspection conducted in Port Angeles, Wash.
The newer tanker, the Alaskan Explorer, was immediately taken out of service May 15 for inspections and remedial work, Beaudo said in a July 14 e-mail. Alaskan Frontier back in service The Alaskan Frontier was back in service at the end of June after repairs were completed at Victoria Shipyards in Vancouver, British Columbia, and sea trials were completed, he said.
Representatives from BP Shipping, Alaska Tanker Co. (BP’s shipping company), shipbuilder National Steel and Shipbuilding Co. and rudder manufacturer Becker Marine Systems worked together on the repairs.
“The trailing edge of the rudder was shortened to reduce tensional bending moments, additional stiffening was added at critical sections of the rudder structure and outer skin plating was renewed where cracks and weakening of the steel was apparent,” Beaudo said.
While work continues to fully understand the failure, preliminary indications are that the failure was related to vibration induced fatigue.
The Alaskan Explorer entered Cascade Shipyard, Portland, July 5 for further inspections and remedial work; it had less damage, as it had been in service a shorter time. Beaudo said the Alaskan Explorer is expected to return to service in early August.
Since the flaws were discovered during inspections, there was never any risk to cargoes or vessels, he said, and other tonnage was available so BP’s ability to move its crude wasn’t affected.
—Kristen Nelson
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