Using PG&E’s inaccurate gas pipeline recordkeeping as an example, the National Transportation Safety Board is recommending that pipeline operators and regulators throughout the U.S. make serious efforts to ensure that the records, surveys and documents for all pipeline systems accurately reflect the pipeline infrastructure as built.

Of the NTSB’s seven safety recommendations, six of them are classified as “urgent” as a result of its investigation into the pipeline rupture and explosion that killed eight people and destroyed 37 homes in San Bruno on Sept. 9, 2010.

The NTSB says the recommendations were issued to address recordkeeping problems that could create conditions in which a pipeline is operated at a higher pressure than the pipe was built to withstand, although it is not known at this time if that is what happened in the San Bruno accident.

In a
letter to PG&E, the NTSB reiterated its findings from an investigative update on Dec. 14 that found that although the records of the pipeline operator indicated that the pipeline in the area of the rupture was constructed of seamless pipe, it was instead, at least in part, constructed of longitudinal seam-welded pipe. In addition, some of the seams of this section of pipeline were welded from both the inside and the outside of the pipe, while others were welded only from the outside.

The NTSB says it is concerned that the 1956-era seam-welded sections may not be as strong as the seamless pipe that was indicated in PG&E’s records. Because it is critical to consider all of the characteristics of a pipeline in order to establish a safe maximum allowable operating pressure (MAOP), the NTSB says it believes that these inaccurate records may lead to potentially unsafe MAOPs.

To address this issue, the NTSB issued three safety recommendations, two of which were classified as urgent, to PG&E asking the utility operator to do the following: 1) Conduct an intensive records search to identify all the gas transmission lines that had not previously undergone a testing regimen designed to validate a safe operating pressure (urgent recommendation); 2) Determine the maximum operating pressure based on the weakest section of pipeline or component identified in the records search referenced above (urgent recommendation); and 3) If unable to validate a safe operating pressure through the methods described above, determine a safe operating pressure by a specified testing regimen.

Because the NTSB says it is concerned that other pipeline operators in the U.S. may also have discrepancies in their records, the board made an urgent recommendation to the Pipeline and Hazardous Materials Safety Administration (PHMSA) to expeditiously inform the pipeline industry of the circumstances of the San Bruno accident and investigative findings so that pipeline operators can proactively implement any corrective measures for their respective pipeline systems.

And as for PG&E’s reaction to this latest request? Kirk Johnson, PG&E vice president, Gas Engineering and Operations, says that the utility is giving these recommendations “close and immediate attention.”

“We have been undertaking an intensive review of our pipeline records, scrutinizing and verifying thousands of documents to confirm the quality of our data,” Johnson says. “We are managing this process across PG&E’s system as part of our ongoing commitment to place the highest priority on public safety.”