A ruptured gas pipeline that led to an explosion in a Northern California neighborhood killing 8 people showed no signs of corrosion and was not leaking or dented, federal accident investigators said.
Investigators found no physical evidence of a pre-existing leak in the pipe pieces, nor did they see dents or gouges suggesting that someone struck the pipe with excavation equipment, said the National Transportation Safety Board officials.
But they report did confirm the 30-inch pipe had welding seams, in contrast to previous claims by the ruptured pipeline’s operator, Pacific Gas & Electric, that the pipe was seamless.
“They didn’t know what they had under the ground in this location,” said Rep. Jackie Speier, a California Democrat who represents the San Bruno area.
Speier would like federal pipeline safety regulators to probe whether it was legal for PG&E to have inspected the 1956 pipeline without using the most high-tech methods available, such as sending a robot into the pipe.
Company officials have acknowledged the utility has yet to fully inspect all its high-risk gas lines that run through the most densely populated regions of the state.
The explosion and ensuing inferno torched nearly 15 acres of 1960s-era suburban homes in the hills overlooking the San Francisco Bay. Dozens of people suffered injuries from the blast, and some victims are still in hospital burn units.
PG&E called the pipe “high-risk” in 2007 and received permission from the California Public Utilities Commission to bill ratepayers to upgrade the pipeline. But they dropped the improvement plans the next year.
The NTSB also is investigating why it took PG&E crews nearly 90 minutes to deploy manual valves to stop the flow of gas into San Bruno the night of the explosion.