BP defends Alaska maintenance regime

Anchorage, Alaska — BP Alaska has defended its oil pipeline maintenance regime, which is reportedly being under scrutiny as part of a US grand jury investigation into a major oil spill in the Prudhoe Bay area earlier this year

According to a US official quoted in the Financial Times, BP had failed to meet a commitment given in 2003 to carry out pigging — passing devices through a pipeline to carry out inspection, cleaning and other operations — of its pipelines every five years.

Daren Beaudo, spokesman for BP Exploration (Alaska) Inc. (BPXA) said he could not recall BP giving such a commitment, but added that the company is working through a plan to complete pigging of the Prudhoe Bay Unit transit line.

“We've been in discussions with DOT (US department of transportation) and it’s clear that they think smart pigging every 5 years would be beneficial in helping us manage the lines, and we're working to do this.” Beaudo said in a written statement to Process Engineering

According to Beaudo, the Lisburne line — one of three required by US authorities — has been pigged and smart pigged and preliminary results confirm the line is fit for service. BP, he said, has also completed a segment in the Eastern Operating Area and is committed to completing all pigging by the end of November.

Pigging is only one of the methods used to inspect and maintain crude transit lines, added Beaudo: “The inspection, maintenance and assurance program over the years has incorporated combinations of state-of-the-art ultrasonic, radiographic, magnetic flux, guided wave and electromagnetic inspection techniques.”

The Anchorage-based spokesman went on to explain how the frequency of pig runs throughout the North Slope area varies and why BP does not routinely run scraper pigs or smart pigs in Prudhoe Bay Unit oil transit lines.

According to Beaudo, where pipelines are above ground, they allow for direct inspection of pipeline sections where corrosion is most likely to occur. With buried pipelines, however, smart pigging is the only way to inspect for corrosion without unearthing the pipeline.

“Given the above ground accessibility of North Slope lines and the extensive inspection program already in place, BPXA did not believe it necessary to smart pig every five years,” Beaudo commented. The company, he added, runs around 370 maintenance pigs per year on the North Slope at Prudhoe either because of mechanical issues or because corrosion monitoring suggests it.

The frequency of pigging depends upon many factors including the build up of sediments and other solids such as wax, continued Beaudo.

“Therefore pigging frequency varies significantly on the North Slope and in the industry. For example, the Northstar oil pipeline is pigged every two weeks to prevent paraffin buildup. There's no cause and effect mechanism for the build up of solids and corrosion.

“The unique role we believe solids played in the Oil Transit Line 2-1 leak was that it prevented the appropriate levels of corrosion inhibitor to effectively treat the pipe and kill bacterially-generated corrosion,” he concluded.