updated 10/11/2006 5:08:28 PM ET 2006-10-11T21:08:28

Oil major BP may face another U.S. congressional hearing into corrosion problems at its Prudhoe Bay oil field in Alaska after investigators turned up documents that may undercut claims BP made about its corrosion prevention practices, a congressional committee aide said Wednesday.

BP had been ordered by the U.S. House of Representatives Energy and Commerce Committee to turn over all relevant documents surrounding the corrosion problems at Prudhoe Bay ahead of a Sept. 7 hearing, but committee investigators only recently discovered a 2002 Alaska Department of Environmental Conservation Compliance Order signed by a BP manager.

"It raises more questions than it answers. It is very troubling that this (document) came to light initially not from BP. This is not something they turned over to us," said one committee staff member.

The document reveals that Alaska state regulators ordered BP to run cleaning devices known as pigs inside the oil transit pipelines in May 2002 to improve leak detection systems in the pipelines

BP said this summer it had not cleaned the pipelines with pigs since the early 1990s due to problems handling the sediment produced by the cleaning operations.

Investigators and federal pipeline regulators have questioned BP's decision not to use pigs in the transit lines, saying this practice was out of line with industry standards.

The committee's probe into a spill of more than 200,000 gallons of crude in March 2006 from a corroded pipeline on the western side of the Prudhoe Bay field and the shutdown of the eastern half of the field in August due to further corrosion in a similar pipeline has focused on BP's practice of inspecting pipelines for corrosion with external tools rather than with so-called smart pigs, devices that are sent down a pipeline to scan the inside walls.

BP officials said they did not use smart pigs on the transit pipelines since their corrosion models suggested there was no risk of serious corrosion developing within the lines.

Pigging questions
Under the May 2002 Compliance Order signed by the BP Greater Prudhoe Bay Unit's operations manager, BP agreed to pig part of the eastern oil transit line and to pig the entire western oil transit line as part of a program to improve leak detection systems in the pipelines.

Only three months later, in a letter dated Aug. 14, 2002, Alaskan environmental regulators said they agreed with BP's proposal that the requirements to pig the pipelines be waived.

"This brings us back to the original questions that were not answered at the hearing. Why did BP decide not to pig these pipelines?" said another member of the committee's staff.

A BP spokesman said the company had apologized for not turning over the order but refused to explain the circumstances under which the compliance order was found at BP.

"Absent concealment, it raises a lot of questions why something like this was not found when you've got the kind of scrutiny that this company was under. How this was overlooked is astounding to me," the aide said.

BP was ordered by federal pipeline regulators to clean out the insides of the transit lines with pigs and then to run smart pig inspection tools following the March 2006 spill. The company, however, later claimed it was unable to comply with the order as it did not have access to facilities for disposing of the sediment that would be produced by running the cleaning pigs through the pipelines.

BP's reputation has been tarnished by a string of accidents, environmental incidents and allegations of improper trading in the United States in recent years.

Bob Malone, appointed to head BP's U.S. operations this summer, has made improving the company's safety and environmental record a top priority.

Copyright 2012 Thomson Reuters. Click for restrictions.

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