(Adds details from report on cause of spill)
By Nia Williams
April 21 (Reuters) - Canada's TC Energy on
Friday said a 14,000-barrel oil spill from its Keystone pipeline
in rural Kansas in December was primarily due to a progressive
fatigue crack, which originated during the construction of the
pipeline.
The Calgary-based company released the findings after
receiving an independent third-party root cause failure analysis
(RCFA), as required by regulators.
Keystone's spill into a Kansas creek was the biggest U.S.
oil spill in nine years and prompted a 21-day shutdown of a
portion of the 622,000 barrel-per-day pipeline, which ships
crude from Alberta to U.S. refineries. TC said it has recovered 98% of the spilled product from the
pipeline and cleaned up 90% of the Mill Creek shoreline.
"We are unwavering in our commitment to fully remediate the
site and are taking action on the recommendations from the
RCFA," said Richard Prior, president of liquids pipelines at TC
Energy in a statement.
TC said the RCFA report found the fatigue crack came from a
girth weld connecting a manufactured elbow fitting to the
section of pipe constructed across Mill Creek. The girth weld
was completed at a fabrication factory and met applicable
standards.
During construction, the pipe segment came under
"bending stresses" that initiated a crack in the girth weld and
also led to a deformation in the elbow fitting and a wrinkle in
the adjacent piping, TC said. The design of the weld transition
made the pipe in that location more susceptible to bending.
"This resulted in the initiation of a circumferential
crack in the weld, which led to failure through operations after
over a decade," TC said.
The company said the RCFA findings are consistent with
its own investigation released in February. TC also noted the segment of pipeline where the leak
occurred had always operated within its temperature and pressure
design limits, and never exceeded 72% of its Specific Minimum
Yield Strength (SMYS). (Reporting by Nia Williams in British Columbia and Deep Vakil
and Brijesh Patel in Bengaluru; Editing by Chris Reese, Chizu
Nomiyama and Diane Craft)
