Report on pipeline blast cause finds weld defects

January 21, 2011 8:03:36 PM PST
A new report on the deadly San Bruno pipeline explosion says the pipe was filled with defective welds. That contradicts PG&E's initial report that the pipe was believed to be seamless and not made of welded parts.

The report, issued Friday, raises serious doubts whether PG&E knows the condition of gas pipelines that went into the ground over 60 years ago -- in San Bruno's Glenview neighborhood and elsewhere in the Bay Area.

"They have documented and found multiple defects in the welded sections of the pipeline," Prof. Reinhold Dauskardt said.

Dauskardt, an expert in metallurgy at Stanford University, calls the 77-page report very thorough. The report zeroes in on one particular segment with defective welds that may have caused additional weakness in the pipeline over time.

"The weldment, in fact, only penetrated 55 percent of the pipe," Dauskardt said. "So it had not been welded all the way through?so basically only half of the section side had been filled with the weldment. In addition, it's full of voids, it's got slag inclusions, all sorts of sites that, with operation, would initiate cracks, defects, that would then begin to spread and grow."

The pipeline ruptured on Sept. 9, causing an explosion and fire that wiped out homes and killed eight people.

PG&E issued a statement after the federal report came out, saying, "All pipelines in PG&E's system that are of a size and vintage similar to the line in San Bruno are continuing to operate at pressures that have been reduced by 20 percent -- a measure that builds a significant additional margin of safety into our current operating conditions."

What PG&E did not say is whether it will step up inspections now that federal experts have found defective welds in the San Bruno pipe.

Based on Friday's findings, Dauskardt raises a question -- whether there was an important clue that a catastrophic event was in the making.

"Residents, as I understand, had been reporting smelling gas, clearly seeping out of this pipe through these defects?that were increasing in size, eventually allowing these gases to escape," Dauskardt said. "You would have thought that somebody should have been more cognizant of what was going on."

Reaction was swift from elected officials. Rep. Jackie Speier, D-Calif., who represents the San Bruno area in Congress, released a statement saying, "I am profoundly disturbed The loss of life might have been prevented if PG&E had properly identified the risks it had underground in the Glenview neighborhood."

ABC7 also contacted the California Public Utilities Commission. They have not responded.

PG&E has come up with a plan to simplify the process of rebuilding the San Bruno neighborhood. The utility has offered to buy all 38 lots where homes were destroyed and turn them over to a single developer for reconstruction. It is not clear how many homeowners might go along with the plan, but 10 have already hired their own architects.