RPT-Alaska pipeline plans weekend maintenance shutdown

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By Yereth Rosen

ANCHORAGE, Alaska, July 28 (Reuters) - The Trans Alaska Pipeline will shut down this weekend to allow crews to perform scheduled maintenance projects, the system's operator said on Wednesday.

The shutdown will start on Saturday morning and last up to 36 hours, said Alyeska Pipeline Service Co., operator of the 800-mile (1,280-km) pipeline and its Valdez marine terminal. It is the second scheduled maintenance shutdown of the summer and follows a similar event in June.

Much of the work to be completed will be at the line's pump stations, Alyeska said. Major projects include replacement of a valve at Pump Station 9, located about 105 miles southeast of Fairbanks, and rerouting of underground fuel gas piping at Pump Stations 3 and 4, located 104 miles and 144 miles south of Prudhoe Bay.

"Alyeska's philosophy is to tackle maintenance issues before they become problems," John Baldridge, the company's senior director for pipeline operations, said in a statement.

"The upcoming shutdown includes upgrades along TAPS so that we can continue running the 33-year-old pipeline safely and efficiently."

Year-to-date daily throughput in the pipeline has been 634,350 barrels, less than a third of the peak level of 2.1 million barrels per day achieved in 1988

Major owners of Alyeska are the three main North Slope oil producers -- BP (BP.L), ConocoPhillips (COP.N) and Exxon Mobil (XOM.N). Koch Alaska Pipeline Company and Chevron (CVX.N) unit Unocal Pipeline Co. own minor shares.

None of the work scheduled for the weekend is related to recent problems at Pump Station 9, where a power outage in May triggered a series of events causing the entire line to shut down for days, said Alyeska spokeswoman Michelle Egan.

When it comes to scheduled summer maintenance shutdowns, "We plan these far in advance," Egan said. "It's work that needs to be done when the pipeline shuts down."

Alyeska usually conducts one or two maintenance shutdowns each summer, allowing crews to take advantage of favorable weather and daylight conditions and allowing for coordination with North Slope oil producers, who often do major maintenance projects at the same time, she said.

Separate from this weekend's maintenance work, Alyeska is planning two wide-ranging reviews of its operations, assessing safety and potential risks.

Part of those reviews will investigate the mishaps at Pump Station 9, where the power outage caused pipeline valves to open and resulted in the overflow of about 5,000 barrels of crude oil from a storage tank. The pump station had previously been automated, but is currently staffed with workers on site around the clock, Egan said.

(Editing by Bill Rigby; Editing by Sofina Mirza-Reid)