NTSB: Ruptured gas pipeline hadn't been inspected in 24 years - WOWK 13 Charleston, Huntington WV News, Weather, Sports

NTSB: Ruptured gas pipeline hadn't been inspected in 24 years

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The rupture of a gas pipeline in the Sissonville area of Kanawha County in late 2012 was the result of corrosion in a section of pipe that had not been inspected in 24 years, the National Transportation Safety Board said in a report released March 10.

The rupture of the Columbia Gas Transmission Corp. natural gas pipeline in West Virginia was caused by external corrosion that could have been discovered by the pipeline operator, the NTSB report said.  On Dec. 11, 2012, a 20-inch high-pressure natural gas pipeline 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 Interstate 77, destroyed three homes, and melted the siding on houses hundreds of feet from the rupture site, the report said.

About 76 million standard cubic feet of natural gas worth $285,000 was released and burned. Columbia reported the cost of pipeline repair as $2.9 million. The cost of system upgrades to accommodate in-line inspection was $5.5 million.

"Remarkably, no lives were lost in this accident but the potential for tragedy was clearly there," NTSB Chairman Deborah A.P. Hersman said in a statement accompanying the release of the report. "Inspection and testing improve the chances of locating defects early,and reduce the probability of a catastrophic failure which can have devastating results."

According to the report, 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 that if it had been inspected with an inline tool, the rupture would likely have been prevented.

"Contributing to the poor condition of the corrosion protection systems was the rocky backfill used around the buried pipe," the report said. "Contributing to the delay in the controller's recognition of the rupture was Columbia Gas Transmission Corporation management's inadequate configuration of the alerts in the supervisory control and data acquisition system. Contributing to the delay in isolating the rupture was the lack of automatic shutoff or remote control valves."

According to the report, 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 that 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 was released and burned, which exacerbated the property damage caused by the accident. Had the pipeline been equipped with automatic shutoff valves, the duration of the gas-fed fire would have been reduced.

Click here for the full NTSB report.