Nick Snow
OGJ Washington Editor
WASHINGTON, DC, July 30 -- The US Pipeline and Hazardous Materials Safety Administration ordered Enbridge Energy Partners Ltd. on July 28 to immediately correct deficiencies in its Line 6B crude oil pipeline, which sprung a leak 2 days earlier.
The order from PHMSA’s Pipeline Safety Office said the rupture’s cause is still unknown and investigations are continuing. It also said resuming operations of the 30-in. line, which Enbridge shut down soon after its employees discovered the leak, without corrective actions would threaten property, public health, and the environment (OGJ Online, July 29, 2010).
Jeffrey D. Wiese, PHMSA’s associate administrator for pipeline safety, also cited the pipeline’s age; circumstances surrounding its failure; the line’s proximity to populated areas, public roadways, and high-consequence areas; the hazardous nature of the product the pipeline transports; the uncertainties as to the cause of the failure, and the ongoing investigation to determine the cause as reasons for issuing the order without holding a hearing first.
He said the US Department of Transportation agency’s pipeline safety office found in a preliminary inquiry that the affected segment of pipe, which the National Transportation Safety Board will transport to a metallurgist for examination and failure analysis once it has been excavated, was manufactured by Siderius in 1969. The segment has a ¼-in. thick wall and is grade X-52 submerged arc weld pipe. It has a Polyken tape coating and an impressed cathodic protection system.
PHMSA investigators found that the estimated operating pressure at the site when the pipe began to leak was 425 lb-force psig. The line segment’s maximum operating pressure was 624 psig and the MOP at its Marshall Station discharge set point was 523.
Corrosion reassessments
The pipeline, which originates in Griffith, Ind., and extends east to Sarnia, Ont., was last reassessed for corrosion in June 2009 with ultrasonic technology and, prior to that, in October 2007, with magnetic flux leakage technology, according to the order. It said that Enbridge notified PHMSA on July 15 of an alternative remediation plan for metal loss anomalies found in this survey to consider pipe replacement instead of repair. Using this alternative remediation method would take more time, the pipeline’s owner and operator indicated.
PHMSA’s order said that Enbridge will have to develop and submit a written plan to the agency’s central region director in Kansas City, Mo., before restarting the pipeline. It said that the plan will need to provide for the segment to be adequately patrolled as operations resume, including exposure of the line for 50 ft to examine for corrosion, coating condition, or other issues on either side of the replaced segment.
The incremental startup will need to occur during daylight hours after local emergency response officials have been provided details, PHMSA said. It will have to involve 25% pressure increments, each of which will need to be held for at least 1 hour with sufficient surveillance to assure that no leaks are present. Written approval from PHMSA’s regional director will required before operation resumes.
Once the pipeline is restarted, the order continued, Enbridge will need to maintain a 20% reduction in the line’s operating until the agency’s regional director approves a return to full pressure. It also told Enbridge to submit an integrity verification and remedial work plan to the regional director within 60 days, including results of the failed segment’s metallurgical analysis, a failure history of the line’s entire US portion for the last 20 years, a detailed description of inspection and repair criteria for any anomalies that are excavated, and provisions for continuing long-term periodic testing and integrity verification measures.
PHMSA’s order came a day after Michigan Gov. Jennifer M. Granholm (D) declared a state of disaster in potentially affected areas along the Kalamazoo River below Talmadge Creek from the pipeline leak. The declaration reinforces the state’s efforts to protect residents and the environment by making necessary resources readily available, she said on July 27. It also will let the state’s emergency operations center, which she activated with the order, coordinate local, state, federal, and private sector response efforts.
Contact Nick Snow at [email protected].