Pipeline rupture in Texas triggered large methane plume

A pipeline rupture longer than a bowling lane was responsible for a massive release of the potent greenhouse gas methane over Texas in March, spewing the equivalent of annual emissions from 16,000 American cars into the atmosphere.

Photos of the rupture show a nearly 67-foot long tear along the 16-inch diameter Big Cowboy natural gas pipeline excavated from a dirt road in a remote corner of Texas. The images were obtained through a public information request to the Railroad Commission of Texas, the regulator that oversees oil and gas production in the state. The pipeline operator, a unit of Energy Transfer LP, has said in regulatory filings that the rupture resulted in a release of 52.15 million cubic feet of gas.

Big Cowboy is part of a vast web of gathering lines in the U.S. that have operated outside the purview of federal authorities because historically they were smaller diameter, low pressure lines deemed less of a risk than the transmission conduits that cross state boundaries. But the massive gas release in March underscores how the failure of even small parts of the U.S. gas network can have profound consequences for the climate.

The pipeline likely experienced a “longitudinal seam rupture failure” based on the photos, although a scientific metallurgical forensic analysis is needed to confirm that assessment, said Richard Kuprewicz, a chemical engineer and president of Accufacts Inc., which specializes in gas and liquid pipeline investigations. The only way to reliably avoid that sort of failure is to perform a spike hydrotest, which isn’t mandated for gathering lines under federal requirements, he said.

Energy Transfer disputed Kuprewicz’s assessment and said that it has ruled out a longitudinal seam rupture as a cause, without saying why. The pipe was strength tested at 1.25 times its maximum allowable operating pressure in 1993 before it entered service, the company said.

The Energy Transfer unit detected a failure in its control center at 8:35 a.m. local time March 17 and the system was shut in and isolated by 8:48 a.m. Workers reached the site of the failure at 1:23 p.m. the

same day, according to an incident report obtained through the public information request. The pipeline was repaired and restarted March 20.

The damaged section of pipe has been sent to a lab for analysis and an investigation into what caused the failure is underway. The incident report described the apparent cause of the rupture as “unknown” and didn’t attribute the failure to corrosion.

The release was about 60 miles southeast of the estimated source location of a severe cloud of methane spotted by a European Space Agency satellite on March 17 at 2:23 p.m. local time, according to an analysis of the observation by Kayrros SAS. The estimated emissions rate for the plume of 147 metric tons of methane an hour makes it the worst the French geoanalytics company has attributed to the U.S. oil and gas sector in more than a year.