As a prelude to newly scheduled fact-finding hearings, federal pipeline investigators Monday issued urgent recommendations regarding record-keeping problems it has encountered with Pacific Gas and Electric Co. (PG&E) in the wake of the San Francisco-based utility’s fatal natural gas transmission pipeline rupture in San Bruno, CA, last September.
PG&E officials said the utility will give the National Transportation Safety Board (NTSB) recommendations “close and immediate” attention, and state regulators sent directives to the combination utility and the state’s other intrastate transmission pipeline operators. NTSB has set March 1-2 for two days of en banc hearings in Washington, DC, to gather facts for the technical investigation.
In addition to the directives to PG&E, the federal investigators have asked their sister agency, the Pipeline and Hazardous Materials Safety Administration (PHMSA), to “expeditiously” get the word out to the pipeline industry about the circumstances surrounding the San Bruno tragedy and investigative findings so far “so pipeline operators can proactively implement any corrective measures.”
The bottom line for NTSB is that inaccurate records can potentially “compromise safety.” Three urgent recommendations were directed at the utility, and another three at the California Public Utilities Commission (CPUC), which has already made similar requests of PG&E regarding its records in the aftermath of San Bruno.
The stepped-up regulatory scrutiny comes at a time when other PG&E staffers told NGI Monday that seasonal peak demands will not force it to have to raise natural gas transmission pipeline pressures on lines that were ordered to operate at lower pressure levels in the wake of the Sept. 9 pipeline explosion. It is making this call despite some frigid temperatures and persistent winter storms in recent weeks that put more pressure on the gas system.
NTSB said it continued to be bothered by the fact that PG&E’s records for the segment of the 30-inch diameter pipeline (Line 132) that ruptured indicated it was seamless pipe, while the interim report by the federal investigators last month described pipe constructed with longitudinal seam welds. It further reported that some of the pipe was welded both inside and outside, and other parts only had external welds.
In mid-December following the NTSB interim report, the CPUC ordered PG&E to lower by 20% the maximum operating pressures in parts of its transmission system throughout its territory. As a result, besides the three pipelines on the peninsula in and around San Bruno, the utility has since lowered pressures by 20% in two pipelines in the East San Francisco Bay: a 57.5-mile transmission line from Fremont to Milpitas (Line 131), and a 27.9-mile line from Oakland to Fremont (Line 153).
“[NTSB’s] urgent recommendations call on pipeline operators and regulators [industrywide] to ensure that the records, surveys and documents for all pipeline systems accurately reflect the pipeline infrastructure as built throughout the United States so that maximum safe operating pressures are accurately calculated,” the NTSB announcement said, listing seven recommendations, six classified as urgent.
Federal investigators are concerned that a seam-welded pipe section may not be as strong as the seamless pipe that was indicated in PG&E’s records, noting that these characteristics are “critical” in calculating safe maximum allowable operating pressure (MAOP). Inaccurate record-keeping on pipelines could potentially lead to unsafe maximum pressures, the NTSB said.
Specifically, PG&E was asked on an urgent basis to: identify all transmission pipelines that have not been tested to validate their safe operating pressure and to determine MAOPs based on the weakest sections of each pipeline. A third, nonurgent, recommendation was made to use a specified testing regimen to determine safe MAOPs, if the methods outlined by NTSB cannot be applied.
For the CPUC, the NTSB has asked that state regulators ensure that PG&E “aggressively and diligently” searches its records to determine pipelines that need testing, and then oversees that testing. As a third priority, it asked the CPUC to “immediately” inform California’s intrastate transmission pipeline operators about San Bruno’s circumstances so those operators can implement corrective measures as necessary.
On Monday CPUC Executive Director Paul Clanon wrote to PG&E’s utility CEO seeking assurances the utility can complete the NTSB recommendations and earlier CPUC directives by Feb. 1. Clanon asked for written assurances on the month-long timetable by this Friday. Similarly, he separately wrote to the other intrastate transmission pipeline operators (Southern California Gas Co., San Diego Gas and Electric Co. and Southwest Gas Corp.) directing them to give individual reports to him by Feb. 1 detailing reviews and corrective actions taken on their pipelines.
In regard to the fact-finding effort and scheduled hearings, NTSB Chairman Deborah A. P. Hersman said the San Bruno incident “has exposed issues that merit further attention and have implications for the pipeline infrastructure throughout the country.”
Separately, PG&E has decided there will be no need to increase the pressure on the pipelines running up the peninsula into San Francisco this winter, a spokesperson told NGI Monday.
“We have taken a number of steps to minimize the risk this winter from the lower operating pressures,” the spokesperson said. Those include conservation and other efficiency programs. In mid-December the CPUC ordered PG&E to lower by 20% the maximum operating pressures in parts of its transmission system throughout its territory as the investigation of the fatal San Bruno pipeline blast continues.
The CPUC picked up on part of a NTSB interim report released Dec. 14 (see Daily GPI, Dec. 20, 2010) that referenced results of the tests of the Sept. 9 ruptured pipeline sections showing “longitudinal seams that were fusion-welded from both inside and outside the pipe, or just the outside of the pipe.”
For pipelines with these characteristics, PG&E was ordered last month by the CPUC’s Clanon to: drop the pressure to 20% below each pipe’s maximum allowed levels; assess those pipelines’ integrity with one of four tests; and obtain CPUC authorization to repressure those lines. Since the San Bruno tragedy, the pressure in the three transmission pipelines operating in the areas have been kept 20% below their allowable levels. That also has now been done for two additional pipelines traversing the East Bay area.
PG&E continues to stress within the limits of the ongoing NTSB investigation that no evidence of external corrosion on the ruptured pipe pieces was found, nor any evidence of excavation damage or physical evidence suggesting a pre-existing leak.
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