Pacific Gas and Electric Co. (PG&E) found itself once again under fire last week for admitting it mislabeled high-pressure natural gas pipeline segments on the same set of pipes traversing the peninsula south of San Francisco where the San Bruno, CA, explosion occurred three years ago. State regulators held a show-cause hearing on Friday, putting the utility again on the hot seat.

The utility is being criticized for another instance in which its workers identified and reported to the California Public Utilities Commission (CPUC) mistakes in labeling pipeline segments on Lines 147 and 101 running north-south along the peninsula where the San Bruno tragedy occurred (see NGI,Sept. 13, 2010).

In a filing to the CPUC, PG&E’s Kirk Johnson, vice president for gas transmission maintenance and construction, said the utility has lowered the maximum allowable operating pressure (MAOP) on both the 30-inch diameter pipelines to 330 psig from 365 psig. In Johnson’s testimony to the CPUC, he divulged that the subsequent investigation within the utility turned up three segments on Line 147 that were inaccurately described in company documents.

“The MAOP validation records for Line 147 were among the earliest we developed,” Johnson said. “The issues we identified in our Line 147 documentation revealed gaps in the early stages of our MAOP validation process,” which he said would be “more fully discussed” by experts at the Friday hearing.

The flap comes as PG&E is facing the prospect of multi-billion-dollar penalties for admitted operating failures (see NGI, Aug. 26).

The latest discrepancy again involves records showing pipeline segments as “seamless,” when in fact they included long seams with welds that may be vulnerable. The error in pipe identity was discovered by PG&E workers during a routine leak repair of a segment of Line 147 in San Carlos, CA, near San Bruno. At least one of the segments passed hydrostatic testing in late 2011. However, there were never any safety problems involved, a PG&E spokesperson told NGI last Thursday.

“As we work to build a safety culture within PG&E, these are the types of problems we want to find so we can move forward and take action to fix them,” the spokesperson said. “That is exactly what happened here.”

Meanwhile, the CPUC is demanding a more detailed accounting. The hearing Friday was to examine both the regulatory process and substance of continuing glitches in the pipeline records.