Even though state officials have been asking for the information ever since the San Bruno pipeline blast last September, Pacific Gas & Electric Co. (PG&E) officials are now saying they may never be able to find some of the documents for the utility’s older natural gas pipelines.
In a filing with the California Public Utilities Commission (CPUC), PG&E said it cannot satisfy a state order to come up with what utility officials termed “traceable, verifiable and complete” records on its entire pipeline network.
The CPUC ordered the utility to turn over the documents after the September 9 explosion in San Bruno that killed eight people and destroyed dozens of homes.
Federal authorities have since determined the pipeline failed at a welded seam.
PG&E officials want state regulators to accept “assumptions” about some of its older pipelines.
PG&E failed to meet a March 15 state deadline to submit a detailed accounting of all its older pipelines that have not undergone high-pressure water testing, the inspection method best-suited for detecting flawed welds.
State regulators are seeking to sanction PG&E for shoddy record-keeping in general and on its San Bruno line in particular.
The weld that ruptured on the San Bruno line was a type known as DSAW, or double submerged arc welding. This involves completing welds from both the inside and the outside of the pipe, forming what appears to be an hourglass pattern, with the two welds merging at the center.
PG&E said federal rules and engineering standards consider such welds to be superior to other types and equivalent to seamless pipe.
The federal safety board’s metallurgists concluded the weld that ruptured in San Bruno was incomplete on the inside half of the hourglass pattern, suggesting that welders who put the pipeline together botched the job. The transmission line went in the ground in 1956 and apparently consisted of pipe that PG&E bought sometime after 1948, the company said.