Corrosion Cause of WV Pipeline Blast

Wednesday, March 12, 2014 @ 06:03 PM gHale

A pipeline explosion that sent a plume of fire into the air in Sissonville, WV, in late 2012 was likely the result of corrosion and no inspection of the pipeline in nearly 25 years, according to a federal report released Tuesday.

The National Transportation Safety Board determined the probable causes of the massive explosion after investigating the blast for more than a year, issuing its 38-page final report.

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“Remarkably, no lives were lost in this accident but the potential for tragedy was clearly there,” said NTSB Chairman Deborah A.P. Hersman.

“Inspection and testing improve the chances of locating defects early, and reduce the probability of a catastrophic failure which can have devastating results.”

In December of 2012 a natural gas pipeline owned by Columbia Gas Transmission Corporation broke near I-77 in the Sissonville area. The pipeline rupture sent a ball of fire more than 100 feet into the air, melting highway signs and destroying three houses.

The NTSB determined corrosion on the outside of the 20-inch diameter pipe wall, caused by deteriorating coating and “ineffective cathodic protection” led to the break in the pipe. No one had discovered the poor condition of the pipeline because it hadn’t been inspected after 1988, according to the NTSB.

Major safety issues identified in this investigation were external corrosion mitigation of the ruptured pipeline, supervisory control and data acquisition alert setpoint configuration, use of automatic shutoff valves and remote control valves to improve isolation of high-pressure pipelines, and exclusion of pipelines in the vicinity of highways from integrity management regulation.

As a result of this accident investigation, the NTSB issued three safety recommendations to the Columbia Gas Transmission Corporation and one to the Pipeline and Hazardous Materials Safety Administration.

From the NTSB report:
“The 2012 rupture of a Columbia Gas Transmission Corporation natural gas pipeline in West Virginia was caused by external corrosion that could have been discovered by the pipeline operator.

“On December 11, 2012, a 20-inch high-pressure natural gas pipeline running through Sissonville, W.V., ruptured with so much force that a 20-foot-long segment of pipe was thrown more than 40 feet from where it had been buried. The released natural gas ignited and burned so hot that it heavily damaged the asphalt road surface on an interstate highway, destroyed three homes, and melted the siding on houses hundreds of feet from the rupture site.

“It took the pipeline controller more than 10 minutes to recognize that a rupture had occurred despite the series of alerts he was receiving that indicated the pressure in the pipeline had begun to decay. The shutdown was only initiated after a controller from another pipeline company reported a possible rupture to the CGTC control center.

“Following the rupture, more than an hour passed before the pipeline operator’s field personnel were able to shut down the supply of natural gas to the broken pipe. More than 76 million cubic feet of natural gas released and burned, which exacerbated the property damage caused by the accident. The NTSB said had the pipeline been equipped with automatic shutoff valves, they would have shortened the duration of the gas-fed fire.

“A 30-square-foot area of the ruptured pipeline was found to have suffered from severe external corrosion that reduced the thickness of the pipeline wall to only about 30 percent of what the pipe originally had when it was installed in 1967.

“The ruptured pipe was the smallest diameter of a group of three CGTC pipelines, all of similar age, which traversed the immediate area. The two larger pipelines were in a “high consequence area,” which required more stringent inspections. Both of those pipes were periodically examined with an inline inspection tool. The accident pipeline, however, had not been inspected or tested since 1988. The NTSB said if it had been inspected with an inline tool, the rupture would likely have been prevented.”

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