SAN FRANCISCO (AP) — The pressure increases that Pacific Gas and Electric Co. has acknowledged occurred on the natural gas pipeline that exploded in San Bruno last fall violated federal regulations, according to a report in the San Francisco Chronicle.
Natural safety gas rules provided to the newspaper, at its request, by federal regulators said the utility would have had to inspect the pipeline in San Bruno for weak welds after spiking the pressure on the line in 2003 and 2008, the newspaper reports in its Sunday edition.
A seam in the pipeline has been cited in federal reports as the source of the Sept. 9 blast that killed eight people and left dozens of homes uninhabitable.
The seam would have most likely been discovered during inspections, but PG&E conducted a less expensive test in 2009 that would have detected only corrosion in the pipeline, according to the newspaper.
Safety experts interviewed by the Chronicle said the spikes may have weakened the lines and made them more prone to rupture.
“There is an obligation to say something is not right here,” Richard Kuprewicz, a Redmond, Wash., pipeline safety consultant, said of PG&E’s practices leading up to the blast. “Now you have to take the appropriate action — what is the plan to deal with this,” he told the newspaper.
The U.S. Pipeline and Hazardous Materials Safety Administration issued a statement to the Chronicle that concluded that any intentional boost that pushes an urban gas transmission line beyond legal limits requires the operator to inspect for weakness in the line.
A pipeline operator “may not intentionally exceed (maximum allowable operating pressure) for any reason,” the agency said in its statement.
But the increases in pressure on the San Bruno pipeline were necessary to continue operations on the pipeline, according to PG&E spokesman Joe Molica.
There was also a key difference between what he termed the “continuous operation of a pipeline at a certain pressure, and occasional brief fluctuations in pressure,” he said.