ANCHORAGE, Alaska - The U.S. Pipeline and Hazardous Materials Safety Administration has given Alyeska Pipeline Service Co. a list of proposed corrective measures tied to challenges that have spun off from having too little oil in the 48-inch diameter, 800-mile pipeline.
The agency is concerned that Alyeska Pipeline Service Co., the oil-company-owned business that runs the pipeline, can't check part of the pipeline system for corrosion and that it takes too long to restart the line after shutting it down, among other issues.
A PHMSA investigation found that the trans-Alaska pipeline poses a risk to public safety and the environment and that issues tied to corrosion, inspection and pipeline restarts after shutdowns must be addressed.
The pipeline currently operates at less than one-third capacity from its peak of 2.1 million barrels per day. Less throughput means decreased crude oil temperatures and conditions that lead to corrosion.
The cooler oil allows more buildup on pipeline walls of paraffin, a corrosion hazard. Alyeska inserts cleaning pigs inside the pipe to scrape the paraffin from the walls. "Smart pigs," on the other hand, perform other pipeline maintenance jobs, such as the detection of abnormalities in metal, but the inline inspection tools are at risk of being stopped by paraffin.
Lower temperatures also means water mixed in with crude oil is susceptible to freezing in Alaska's extreme cold if the pipeline is shut down, making re-starts more risky if the pipeline has been involved in a long shutdown.
"There is a risk of water accumulation in low points freezing and creating ice plugs which could impede restart of TAPS and damage valves, instrumentation, and other pipeline components," the letter said. The water itself is another corrosion hazard.
The oil companies that own Alyeska and the pipeline - BP, Conoco Phillips, Exxon Mobil, Koch Industries and Chevron - are finalizing a two-year study on how to manage the risks involved in operating the pipeline as the oil flow rate declines.
Alyeska is also paying for a third-party risk assessment of the pipeline from the North Slope to the ship-loading arms at the Valdez tanker port. The study was requested by U.S. Sen. Lisa Murkowski, R-Alaska, after a big oil spill last year at a Pump Station 9 near Delta Junction.
The two studies are expected to be finalized in the first half of this year.
The proposed safety order in a letter prepared this month follows a January leak at Pump Station 1 on Alaska’s North Slope. A containment vault collected an estimated 13,326 gallons of oil that leaked from a pump station pipe. Still, the pipeline was shut down for days and producers for a time were limited to extracting five percent of capacity.
To fix the leak, the trans-Alaska pipeline was shut down twice for a total of 142 hours. That disrupted as much as $300 million worth of production. The leak was contained inside a building at Pump Station 1 and did not cause environmental contamination, according to regulators.
The agency proposed 13 corrective measures, including replacement of any piping in the system that cannot be assessed with smart pigs or other technology it approves.