Bending stress, weld flaw cause of Kansas Keystone oil spill

WASHINGTON CO., Kan. (WIBW) - Bending stress coupled with a weld flaw has been blamed for an oil spill in the Keystone pipeline that released 14,000 barrels of oil into Washington Co.’s Mill Creek in early December.

TC Energy - the company behind the Washington Co. oil spill of the Keystone Pipeline - announced on Thursday, Feb. 9, that it continues to clean the spill and investigate the root cause.

The Canadian oil company said an independent mechanical and metallurgical analysis of the failed pipe has been completed. It found the failure happened due to a combination of bending stress on the pipe and a weld flaw at a fitting girth that was done at a fabrication facility.

While TC Energy said the welding inspection and testing were held within applicable codes and standards, the flaw led to a crack that grew over time as a result of bending stress which led to the rupture. The cause of the bending, however, remains under investigation.

The company also indicated that the metallurgical analysis found no issues with the strength or material properties of the pipe or manufactured fitting. It operated within its operational design and within the maximum operating pressure.

“Our focus continues to be the safe operation of the pipeline system,” said a TC Energy spokesperson. “Additional operational mitigations, such as reduced operating pressure, are in place to support the safe operations of our system while we continue our response and investigation. Our team is progressing a remediation plan, including an analysis of other areas with potentially similar conditions, the use of additional in-line inspections, and further operational mitigations.”

TC Energy noted that since the early-December spill, it has revised the release volume of the pipeline to 12,937 barrels from the estimated maximum of 14,000. The revised volume is the actual measured volume of oil injected during the re-fill of the system during its safe restart.

The company said its commitment to remediation, investigation and shared information will not waver. To support this, it said it has arrived at a cost estimate of $480 million to be adjusted as it continues to progress work on site. Insurers are in the loop to maximize cost recoveries.

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