A report released Friday by the National Transportation Safety Board has indicated there were faulty welds on a pipeline that exploded in a San Bruno neighborhood Sept. 9, claiming eight lives and destroying dozens of homes.
Line 132, which was installed under the Crestmoor Canyon neighborhood in 1956, was initially believed to be "seamless," according to PG&E, and not made of welded parts.
But the metallurgical report released Friday said a weld on the pipe had "overstress from the root of the weld."
Rep. Jackie Speier, D-San Mateo, said she is "profoundly disturbed by what I read today.”
"Over the past several months, experts have told me that welding flaws are detectable," she said in a released statement.
She said that PG&E believed the pipe was seamless and its crews "never once inspected the condition of the welds."
There had previously been reports by San Bruno residents that there was a natural gas smell in the neighborhood before the explosion, which could have indicated that the pipeline was leaking before it ruptured.
But the NTSB found in a December report that there was no physical evidence of a pre-existing leak in any of the ruptured pipe pieces.
The earlier report found that the ruptured piece of pipe showed no evidence of corrosion, and no dents or damage that could have been inflicted during construction.
"While additional work still lies ahead to reach a final conclusion on what caused the Sept. 9, 2010 tragedy in San Bruno, today's metallurgical report by the NTSB is another important step in that process," PG&E President Chris Johns said in a released statement.
"We are continuing to fully cooperate with NTSB and others," Johns said.