No injuries were reported, though several homes were damaged, when the pipeline burst in Sissonville, W.Va., near Charleston.
The National Transportation Safety Board said the high-intensity blast blew a 20-foot section of pipe more than 40 feet from its original location. The external corrosion that caused the rupture could have been discovered by CGTC, the pipeline's operator, the regulator said.
"Inspection and testing improve the chances of locating defects early, and reduce the probability of a catastrophic failure which can have devastating results," NTSB Chairman Deborah Hersman said in a statement Monday.
NTSB said it took operators more than 10 minutes to recognize the rupture despite a series of alerts. More than an hour passed before personnel were able to shut off the gas and more than 76 million cubic feet of natural gas burned following the pipeline break.
CGTC in a statement said it would take a lessons-learned approach to the incident.
"We also look to better obtain, interpret and apply information on our systems to ensure safe and reliable operation," it said.
The NTSB report was delayed because of the 16-day partial government shutdown caused by a congressional dispute on budget issues in October.