TC Energy says stress, weld fault caused Keystone oil spill

Moscow, February 10 - Neftegaz.RU. Pipeline operator TC Energy Corp said on Thursday a combination of factors including bending stress on the pipe and a weld flaw might have led to the Keystone oil spill and that it was expecting $480 million in costs related to the incident.

TC Energy Corp said:

• We have advanced our root cause investigation with the completion of an independent mechanical and metallurgical analysis of the failed pipe.
• The analysis concludes that the failure occurred due to a combination of factors, including bending stress on the pipe and a weld flaw at a pipe to fitting girth weld that was completed at a fabrication facility.
• Although welding inspection and testing were conducted within applicable codes and standards, the weld flaw led to a crack that propagated over time as a result of bending stress fatigue, eventually leading to an instantaneous rupture.
• The cause of the bending stress remains under investigation as part of the broader third-party root cause failure analysis.

The metallurgical analysis identified no issues with the strength or material properties of the pipe or manufactured fitting. The pipeline was operating within its operational design and within the pipeline design maximum operating pressure.

• We have revised the release volume to 12,937 barrels from the original estimated maximum of 14,000 barrels. The revised volume is the actual measured volume of crude oil injected during the re-fill of the pipeline system during its safe restart.
• Our commitment to remediation, investigation and shared learnings is unwavering. To support this, we have arrived at a cost estimate of US$480 million. This estimate may be adjusted as we continue to progress work on site. We have appropriate inusrance coverage in place and are working with our insurers to maximize cost recoveries.