Bad information in the Pacific Gas and Electric Co. (PG&E) recordkeeping system for the segment of natural gas transmission pipeline that ruptured in San Bruno, CA, last September did not affect the utility's risk management analysis or assessment methodology for the flawed segment (180) on PG&E Line 132, the utility concluded in a report filed Monday with the California Public Utilities Commission (CPUC).
As part of its report, the San Francisco-based combination utility urged that the nation's -- not just California's -- aging pipeline infrastructure be "reevaluated and validated" as safe, and that regulators and operators discontinue the practice of using historic operating pressures to establish safe future operating levels.
The public portion of the 110-page document is part of the CPUC's ongoing proceeding attempting to investigate the utility's gas pipeline system operations and practices related to its records that drew strong criticism early this year from the National Transportation Safety Board (NTSB) as part of its ongoing investigation into the cause of the Sept. 9 San Bruno explosion (see Daily GPI, Jan. 5).
The CPUC specifically asked PG&E to answer the question: "Does [it] contend that the...San Bruno pipeline rupture was unpreventable by the exercise of prudent utility safety care?"
NTSB had cited the fact that PG&E's pipeline records had described Segment 180 as "seamless" when it in fact was longitudinally welded. PG&E's response was that it didn't make any difference. "The record discrepancy did not impact [the utility's] risk management treatment of Segment 180 or Line 132," PG&E said.
Had the fatal segment of pipe been correctly identified as a "double submerged arc welded" (DSAW) piece of pipe, instead of mislabeled "seamless," it would not have changed the integrity management assessment methods applied by the utility under its integrity program. Direct assessment methods are used in this case because internal or external corrosion and stress corrosion cracking were threats that reasonably could be expected to exist in Line 132, PG&E said in its report to the CPUC.
The mislabeling of the segment as seamless, PG&E now has concluded, dates back to 1956 when a journal voucher and other construction documents were filled out and filed on the pipe. That bad information was carried on in ensuing decades and picked up in the mid-1990s when PG&E created its electronic geographical information system, which was the source of the data reported to NTSB.
PG&E urged the CPUC and other regulatory bodies to evaluate the utility's recordkeeping in the context of the rules in place at given periods of time. "Recordkeeping issues extend well beyond PG&E," said the utility, citing the current NTSB chairman (Deborah Hersman), who earlier called for a "culture of safety, making sure that aging infrastructure is not exempted from safety requirements, and keeping records not just for your successor, but for your successor's successor."
In submitting its latest responses to an increasingly skeptical state regulatory commission, PG&E said it plans to file additional information in June while recognizing that "better recordkeeping requirements" must be implemented industrywide.
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