Keystone Pipeline Failure Traced to Fatigue Crack
Pipeline fatigue was what caused the leak of thousands of barrels of oil from the Keystone Pipeline earlier this year in North Dakota. The spill spread across farmland and required significant cleanup efforts. The cause became public this week after the pipeline operator released new information.
AP Confirms Failure Originated in Long-Seam Weld
The Associated Press reported that in a quarterly filing, pipeline operator South Bow said initial findings show “the failure resulted from a fatigue crack that originated along the pipe’s manufactured long-seam weld.”
Analysis Shows Materials Met Industry Standards
South Bow stated that a mechanical and metallurgical analysis found the pipe and its welds met industry standards. The analysis concluded that the crack did not stem from an out-of-specification weld or improper materials.
Pipeline Safety Trust Explains Fatigue Crack Growth
The AP quoted Pipeline Safety Trust Executive Director Bill Caram, who explained that a fatigue crack grows larger “with changes in pressure over time.” He said the failure is consistent with the type of crack that slowly expands during routine pressure cycles on a high-volume crude pipeline.
Pressure Cycles Contributed to Weld Weakening
Caram said pressure cycling can steadily worsen a weld flaw until it ruptures. South Bow did not release more technical details about the segment involved or whether similar weld areas will undergo expanded inspection.
Spill Spread Across Farmland Before Containment Efforts
The oil spill spread over agricultural land in North Dakota before responders contained the release. The AP report did not provide new details on cleanup volumes, remediation progress, or potential regulatory actions. South Bow has not disclosed additional steps it may take to review or reinforce the pipeline in light of the weld-fatigue finding.
The cause announcement marks a key stage in the investigation, and regulators are expected to review South Bow’s full analysis as more required federal documentation becomes available.
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