A crack caused a pipeline rupture leading to a wildfire in west-central Alberta in 2024, according to a report released on Thursday. The Transportation Safety Board of Canada (TSB) disclosed its findings regarding the rupture of a natural gas pipeline near Edson, Alberta, situated approximately 200 kilometers west of Edmonton.
The report indicated that at around 10:45 a.m. on April 16, 2024, a 36-inch pipeline carrying sweet natural gas ruptured about 36 kilometers northwest of Edson. Nova Gas Transmission Ltd., a subsidiary of TC Energy Corp, owned the pipeline.
An investigation revealed that stress corrosion cracking, resulting from a combination of soil conditions, degraded protective coating on the pipeline, and increased internal pressure, caused the pipeline rupture. Soil testing at the site showed microbiological activity capable of corroding the steel of the pipeline. The compromised external coating exposed the steel to environmental elements, leading to potential corrosion.
On the day of the explosion, the pipeline’s pressure was raised to its highest operating level ever experienced at the location, causing the crack to fully rupture.
The report also mentioned that the crack leading to the rupture was detected in a 2022 in-line inspection but was classified as non-reportable. A team of analysts from Baker Hughes downgraded the identified crack to a non-reportable “metal loss” feature, resulting in it being excluded from TC Energy’s inspection and risk assessment processes.
TC Energy expressed its commitment to collaborating with its inspection vendors to enhance integrity management practices following the incident. Baker Hughes acknowledged the TSB report’s findings and outlined plans to improve inspection technologies and services.
The report further detailed the aftermath of the rupture, noting that the ignited natural gas led to an explosion, creating a seven-meter-deep crater. Approximately 20 meters of the pipeline was ejected due to the explosion, with the largest debris piece launched 200 meters away. The escaping gas burned until self-extinguishing at 1:45 p.m., releasing nearly six million cubic meters of gas and causing a wildfire that scorched over 60 hectares, yet resulted in no injuries.
The ruptured pipeline section was replaced and resumed service under reduced operational pressure on May 27, 2024.