A US federal agency says a leak in TransCanada Corp.'s Keystone oil pipeline in South Dakota was likely caused by damage during construction in 2008.
In a corrective action order on Tuesday, PHMSA said its investigation is ongoing, although its preliminary findings showed TransCanada and PHMSA identified the source of the release on 26 November.
“The rupture has characteristics of mechanical damage from original construction,” it said. “Preliminary information indicates the failure may have been caused by mechanical damage to the pipeline and coating associated with a weight installed on the pipeline in 2008.”
The crude pipeline must operate at a 20% pressure reduction after it restarts, the US pipeline regulator said on Tuesday, nearly two weeks after the line was shut after it leaked 5000 bbls of oil in South Dakota.
TransCanada shut the 590 000 bpd pipeline, one of Canada’s main crude export routes linking Alberta to US refineries, on 16 November after a leak was detected.
The pipeline restarted on Tuesday.
The pipeline was constructed from June 2008 until March 2010. Weights are placed on the pipeline in areas where water could potentially result in buoyancy concerns.
TransCanada has removed the portion of pipeline containing the failure location and will ship it to a lab for testing.
It is not clear when the pressure restriction will be removed.
South Dakota officials do not believe the leak polluted any surface water bodies or drinking water systems.
Read the article online at: https://www.worldpipelines.com/equipment-and-safety/29112017/cause-of-keystone-spill-likely-to-be-mechanical-damage/