A federal investigation into a fatal natural-gas pipeline explosion in rural Coolidge two years ago has concluded that the incident was caused by gaps in protective tape wrapping that led to water leakage, corrosion, and cracks along a seam weld, AzCentral news blog reported.
According to the reports, the National Transportation Safety Board (NTSB) released a report on April 27, stating that pipeline owner Kinder Morgan likely underestimated corrosion risks due to an incorrect listing of a stronger type of protective coating in its database.
The explosion occurred in the early morning hours of August 15, 2021, resulting in a fire that destroyed a farmhouse located 451 feet away, leaving two dead and one injured. The blast propelled a 47-foot segment of pipe 133 feet from the blast crater, causing damage to approximately 33 acres of vegetation. Workers successfully shut down the gas flow after nearly three hours.
Kinder Morgan estimates the blast and subsequent fire caused approximately $5.5 million in combined property damages and emergency-response expenses.
While neither the company nor the NTSB report provided specific details about the victims, news reports have identified them as Luis and Valeria Alveraz, a father and daughter. The injured victim was the wife and mother of the deceased.
Kinder Morgan stated that no pending litigation was reported as of their most recent annual report released on February 8, 2023. The company notified its insurers about the incident and did not anticipate any significant adverse impact on its business resulting from the resolution of legal claims.
The Arizona pipeline, originally installed in 1986 by All-American Pipeline Co., was designed to transport crude oil from west to east. Over the years, it became a part of El Paso Natural Gas and eventually Kinder Morgan in 2012. The 1,540-mile-long pipeline, which spans across Arizona and California, was converted to natural gas transmission in 2002 and 2003, with the flow direction altered westward.
As the main protection against corrosion, the pipeline was coated with two layers of spiral wrap tape. However, according to the NTSB report, Kinder Morgan's records erroneously listed the coating type as "fusion-bonded epoxy," potentially leading to an underestimation of the corrosion risks.
Investigation findings revealed that cracks leading to the rupture had formed and merged on the outer surface of the pipe near a seam weld. The NTSB report emphasized that spiral wrap tape is more susceptible to the type of corrosion that damaged the pipe, unlike fusion-bonded epoxy, a powder coating.