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Corrosion, inspection practices and other conditions on the 800-mile Trans-Alaska Pipeline are endangering the public and the environment, and pipeline owners must address them now, the U.S. Pipeline and Hazardous Materials Safety Administration has ordered.
PHMSA launched an investigation of the pipeline in the wake of a leak that began Jan. 8 at Pump Station 1 (PS-1). The pipeline was shut down for four days, leaking about 1.8 gallons of oil each minute into a containment area. The cause of the leak is assumed to be corrosion in the concrete-encased pipe, although the pipe has not yet been excavated.
On Feb. 1, in a Notice of Proposed Safety Order, the agency informed pipeline owner Alyeska Pipeline Service Co.: “As a result of the investigation, it appears that multiple conditions exist on your pipeline facility that pose a pipeline integrity risk to public safety, property or the environment.”
The agency spelled out a list of corrective measures to be undertaken by Alyeska, a consortium of oil and gas companies led by BP.
Less Oil, More Corrosion
The 48-inch diameter pipeline carried about 2 million barrels per day (BPD) at its peak in 1988. At the end of 2010, however, it was averaging only 600,000 to 700,000 BPD.
That reduction “has resulted in numerous integrity challenges that have not been fully addressed” by Alyeska, PHMSA said.
Those issues include decreasing crude oil temperatures, water freezing due to the decreased temperatures, increased build-up of wax on the pipeline walls, slack line conditions at multiple locations, and changing oil composition.
Most damaging are a present pipeline specification that allows crude oil containing up to 0.35% Basic Sediment and Water to enter the system, which does not prevent free water and water slugs from entering the crude stream. During a cold-weather shutdown, water can accumulate in low points, freeze and create ice pugs. Ice crystals in the crude stream can damage equipment and instrumentation.
Also serious is the excessive wax buildup on the walls at lower crude temperatures, which contributes to a corrosion-conducive environment and interferes with smart pig inspections.
History of Corrosion, Wall Loss
The agency noted a history of “both internal and external corrosion problems on pipeline” upstream of PS-1 that has already led to replacement of several pipelines. In 2008, the agency noted, Alyeska identified several locations with internal corrosion, including two locations with more than 80% wall loss and three with more than 50% wall loss.
The agency also noted that Alyeska created a Cold Restart Plan in 2001 but had never used it until last month, when Alyeska was unable to implement the plan without disregarding certain regulatory requirements.
Corrective Measures
The agency proposed 13 corrective measures, including:
• A written plan for a third-party investigation of the leak site at PS-1. The investigation must include sampling of sediments, deposits and bacteria, and sections of pipe must be provided to PHMSA for its own analysis.
• Replacement of any piping in the system that cannot be assessed with smart pigs or other technology the agency approves.
• An assessment of the need for using additional pig launchers and receivers, assuming continued reduction in the pipeline throughput.
• A written plan and timeline for installing at least one additional permanent pig launcher and permanent pig receiver between PS-5 and PS-10.
• Revising the Cold Restart Plan, including lessons learned from the January shutdown.
• Evaluation of the need for increased tank capacity at pump stations to assist in collecting oil during prolonged outages and the implementation of a cold restart.
Company Response
Alyeska spokeswoman Michelle Egan told the Associated Press that Alyeska had requested a meeting with PHMSA to discuss the order.
"There are several [items] that we disagree on, and there are also several items in there that we have already begun," Egan said.
She said the company was well aware of issues associated with fewer barrels of oil in the pipeline.
"We believe that the pipeline is safe and that there are challenges that are associated with such things as low throughput. It's a large, complex system that we manage within the risks," she told the AP.
Protective Coatings
Protective coatings are used throughout the pipeline project: in superstructures for the berths at the Valdez Marine Terminal, in the concrete-ballasted buried pipeline, and in the Valdez terminal storage tanks.
Corrosion prevention and control is a critical focus on pipeline operation and maintenance, Alyeska says.
Corrosion monitoring includes about 800 coupons along the 380 miles of buried pipeline and then-new equipment at PS-1 in 2007, Alyeska said.
Rep. Edward Markey (D-MA), ranking Democrat on the U.S. House Natural Resources Committee, has said that the monitoring is insufficient.
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