Today, TC Energy and the Pipeline and Hazardous Materials Safety Administration (PHMSA) received the independent, third-party Root Cause Failure Analysis (RCFA) for the Milepost 14 incident on the Cushing Extension of the Keystone Pipeline System. This concludes the third-party investigation outlined by PHMSA’s Amended Corrective Action Order (ACAO).
“We are unwavering in our commitment to fully remediate the site and are taking action on the recommendations from the RCFA. We will not stop until we have completed this work. We safely restarted the Keystone System in December 2022 and remain confident in its reliability as we deliver the energy the continent relies on.
We have made significant progress on our remediation and, to date, recovered 98 percent of the released product and cleaned up 90 percent of the Mill Creek shoreline. We are grateful to the agencies and personnel who continue to support this response, including the U.S. Environmental Protection Agency (EPA), the Kansas Department of Health and Environment (KDHE) and approximately 3,000 skilled personnel. Our team has achieved over 1 million person-hours in support of the commitment to this response and the safety of our system.” – Richard Prior, President, Liquids Pipelines, TC Energy
We are sharing the key findings of the RCFA and immediate actions.
The RCFA revealed that a unique set of circumstances occurred at this location, which originated during the construction of the pipeline segment, and led to the failure at Milepost 14.
- The primary cause of the rupture was a progressive fatigue crack that originated at a girth weld connecting a manufactured elbow fitting to the pipe constructed across Mill Creek. This girth weld transitioned the pipe wall thickness from the elbow fitting to the adjacent piping and was completed at a fabrication facility. The RCFA confirmed the welding workmanship was compliant with applicable codes and standards.
- During construction, the pipe segment was subject to inadvertent bending stresses sufficient to initiate a crack at a shallow lack of fusion feature in the girth weld. Bending stresses during construction also led to a deformation in the elbow fitting and a wrinkle in the adjacent piping. Further, the design of the weld transition created a stress concentration point, making the pipe at this location more susceptible to bending stresses. This resulted in the initiation of a circumferential crack in the weld, which led to failure through operations after over a decade.
- The findings are consistent with the initial metallurgical and mechanical investigation released in February 2023, which also noted the elbow fitting and pipe met all strength and material property design and code requirements.
- The report notes that throughout its operational history, the Milepost 14 segment operated below its temperature and pressure design limits; this section of the Keystone system has never operated above 72 percent Specific Minimum Yield Strength (SMYS).
Our learnings and commitment to action
We are in the process of implementing a comprehensive plan – including the RCFA’s recommendations – to enhance our pipeline integrity program and overall safety performance. This plan will evolve.
- Excavations to investigate other sites with characteristics like the incident location sites based on the findings of the RCFA and our remedial work plan. We have taken steps to ensure the system is safe and reliable while this work is performed, including operating the system at reduced pressure.
- Performing additional in-line inspections as part of our system-wide response to the incident. To date, we have completed in-line inspections on the entirety of the Cushing Segment, the segment where the Milepost 14 incident occurred, which amounts to approximately 300 miles (482 kilometres).
- Reviewing and evolving pipeline design guidelines, construction, operations and integrity management practices.
Community and industry collaboration
We appreciate the ongoing oversight and expertise of the U.S. EPA, KDHE, PHMSA and other local, state and federal agencies. Our team remains grateful for the continued support of the Washington County community.
In support of our steadfast commitment to safety, we will also continue to share the learnings from the Milepost 14 incident and investigation with the broader industry to prevent similar incidents occurring elsewhere.