NTSB: Segment of Pipeline that Exploded Had Number of Defective Welds

A report released today by the National Transportation Safety Board showed that the welds found on the pipeline that exploded on Sept. 9 in the Crestmoor neighborhood, leaving eight people dead and 38 homes destroyed, had a number of defects.

Line 132, which was installed under the neighborhood in 1956, was initially believed to be seamless, according to PG&E, and not made of welded parts.

But the NTSB’s recent preliminary report on the explosion showed that, in fact, the pipeline had a number of longitudinal seams in it. The 78-page metallurgical report released today supported that evidence by pointing to numerous defective welds along the pipe’s longitudinal seams.

“What it’s telling us is that it looks like one of the seam welds failed,” said Rick Kuprewicz, a pipeline safety expert. “It also tells us there were serious problems related to the construction of the pipe.”

Following the release of the initial findings about the welds in Line 132, the NTSB issued several urgent recommendations to Pacific Gas & Electric Co. to thoroughly examine its records to identify all of its gas transmission lines that haven’t undergone proper testing for safe operating pressures.

Kuprewicz said the information released today validates why those recommendations were urgent and raises the question of whether the utility may have missed these defects in other lines.

Congresswoman Jackie Speier said the report identifies a “weak link” in PG&E’s pipeline system and that she was unsettled by the fact that it took so long to identify the risks.

“I am profoundly disturbed by what I read today,” Speier said in a statement. “Over the past several months experts have told me that welding flaws are detectable. We know that PG&E believed this pipe was seamless and that in 54 years it never once inspected the condition of the welds. The loss of life might have been prevented if PG&E had properly identified the risks it had underground.”

Speier said she will be meeting next week with the NTSB, PG&E, the California Public Utilities Commission and the Pipeline and Hazardous Materials Safety Administration to identify other pipelines in the Bay Area that may have welds similar to the ones found on Line 132, accelerate PG&E’s examination of its records and work with federal regulators on crafting new rules for inspecting pipe welds.

Today’s report is the first of six factual reports the NTSB’s expects to release as part of its ongoing investigation into the pipeline explosion. The cause of the explosion has still not been determined.

"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 statement. "We are continuing to fully cooperate with NTSB and others.”

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