External corrosion under the insulation caused the May 15, 2015, rupture of a Plains All American crude oil pipeline in California, the US Pipeline and Hazardous Materials Safety Administration said in a preliminary report from its ongoing investigation of the incident.
The rupture in Santa Barbara County allowed more than 500 bbl of crude to leak into a nearby state park and ultimately the Pacific Ocean (OGJ Online, May 20, 2015). PHMSA still is investigating the incident and plans to issue a final report later this year, the US Department of Transportation agency said as it released the initial report on Feb. 17.
It said the report includes details from the required metallurgical analysis of the failed pipeline section following the event, and a third-party review of in-line inspection (ILI) results for Lines 901 and 903. Plains conducted ILI surveys on Line 901 to assess the integrity of the pipeline in 2007, 2012, and 2015, PHMSA noted.
PHMSA’s final incident investigation report will incorporate all aspects of the events leading up to the release and all contributory causes, including details as to the specific cause of the external corrosion and information about the operator’s adherence to federal regulations regarding the operation of Lines 901 and 903, PHMSA said.
It said that it has required the pipeline’s operator, Plains Pipeline LP in Houston, to take a number of actions to restore and rehabilitate the safety and integrity of their pipelines.
PHMSA said that its review of the Plains pipeline’s internal inspection results, which the operator conducted before the failure, discovered instances where the inspection tool miscalculated the degree of corrosion occurring in specific portions of Line 901 and Line 903. As a result, PHMSA ordered Plains to remove all crude oil from Line 903 to reduce the risk of corrosion and any impact the pipeline’s safety and integrity, the agency said.
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