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Corrosion infested Prudhoe pipeline
Anchorage Daily News


November 01, 2006

ANCHORAGE, Alaska -- The leaky pipeline that led to this summer's market-rattling Prudhoe Bay oil field shutdown was far more severely corroded than initially reported.

BP, the company that runs Prudhoe, originally disclosed 16 "anomalies" along the pipe - places where corrosion had chewed either partly or fully through the steel pipeline wall.




But according to a test report obtained by the Daily News, the three-mile pipeline was infested with 5,476 potential bad spots, including 176 places where corrosion might have chewed through 50 percent or more of the pipe wall.

BP's Alaska spokesman and its corrosion manager say the company was surprised by the test results, which were generated by a bullet-shaped electronic device called a smart pig that slides through a pipe looking for bad spots.

A BP contractor, BJ Pipeline Inspection Services, ran the pig through the so-called Flow Station 2 pipeline - a key trunk line that drains oil out of the eastern side of the sprawling Prudhoe field - on July 21.

Sixteen days later, the pipeline sprang leaks that, coupled with the alarming test report from the pigging run, prompted top BP executives to shut down half of the nation's largest oil field as a precaution, an event that unnerved global oil and gasoline markets.

BP carried out the pig run only after federal pipeline regulators had ordered it to do so.

The British oil giant already had drawn scrutiny from the regulators, as well as from members of Congress and federal criminal investigators, following a separate pipeline leak elsewhere in the field back in March.

That leak, from another corroded segment of pipe, resulted in an estimated 201,000 gallons of crude oil spilling onto the tundra - the largest oil spill ever in the North Slope oil fields.

BP executives have admitted that the company's corrosion inspection program was flawed and that the pipes of the type that leaked weren't being monitored adequately.

The company has committed to replacing a total of 16 miles of these pipelines, known as oil transit lines.

Thomas Barrett, head of the U.S. Pipeline and Hazardous Materials Safety Administration, said the BJ Services pigging report showed BP wasn't doing the job.

"It reinforces that they didn't properly clean or maintain the line," he said. "They didn't understand the condition of the line, and this condition was allowed to build up over time. I think the maintenance standards there were well below what we expected."

According to the BJ Services report, the smart pig - a highly magnetic device that uses sensors to check the pipeline wall for bad spots - found a total of 5,476 places where the 0.34-inch wall thickness was worn away to some degree.

Most of the hits were for internal damage, or places where corrosion had chewed pits into the pipe's inner wall, as opposed to attacking from the outside. The pipe is 30 inches in diameter.

Water touching steel typically is what gets corrosion started.

BP managers said they were surprised that its transit lines were so badly corroded, because they carry mainly pure crude oil with little water mixed in.

Barrett agreed that severe corrosion in such oil transit lines elsewhere in the country is uncommon.

Other pipelines within Prudhoe's vast network of some 1,500 miles of lines are much more susceptible to corrosion and BP spends tens of millions of dollars to fight that corrosion and prevent leaks, said Bill Hedges, the company's Alaska corrosion manager. He said BP is still trying to figure out what caused the corrosion outbreak inside the transit lines.


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Scripps-McClatchy Western Service,

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