The rupture of a section of a Columbia Gas Transmission Corp. natural gas pipeline in Sisson, WV, in late 2012 was caused by severe corrosion that could have been detected with regular inspections, the National Transportation Safety Board (NTSB) reported Monday.
A section of the pipe in Sisson, which is about 14 miles from Charleston, ruptured in December 2012, destroying three homes and melting a section of Interstate 77 (I-77) (see Daily GPI, Dec. 17, 2012). No one was injured. A preliminary report by NTSB a month later indicated the pipe wall where the rupture had occurred on the 20-inch diameter line was at about 30% of its original size (see Daily GPI, Jan. 17, 2013; June 12, 2013). Those findings were confirmed in Monday's final report.
The buried pipeline was installed in 1967 and had not been inspected or tested since 1988.
NTSB investigators also expressed concern about gas transmission pipelines near arterial roadways such as I-77 and recommended that the Pipeline and Hazardous Materials Safety Administration add interstates and roadways, such as expressways and freeways, to a list of sites identified as high consequence areas, which require more stringent inspections.
"The Sissonville pipeline rupture caused major damage to I-77," NTSB said. "An intense fire raged directly across the interstate for nearly an hour. Had the accident occurred during commuting hours, when traffic would have been significant, severe or fatal injuries could have occurred." Closing arterial roadways for several hours significantly may affect first responders, commuters and commerce, investigators said.
Columbia's response to the incident was delayed by an inadequate alert system and the lack of automatic shut-off or remote-control valves, according to the report.
Before the incident, Columbia's supervisory control and data acquisition system had issued a series of alerts over a 12-minute period that indicated pressure was dropping, the report noted. However, the control center controller did not recognize the significance of the alerts nor begin to shut down the system until a controller with another pipeline system reported the possible rupture, said officials.
The rupture released more than 76 MMcf of natural gas, which burned off. Fire damage extended along almost 1,100 feet of the pipeline right-of-way, with a 20-foot section of pipe hurled more than 40 feet.
NTSB recommended that Columbia modify its control and data acquisition system to provide operating trend data that may be used to evaluate the significance of a change. Trends that would be likely to cause significant system malfunctions should have an alarm assigned to them.
Columbia "is committed to operating safely and doing whatever we can to ensure that will be the case," said a spokeswoman in response to the report.