Pacific Gas and Electric Company (PG&E) said that it will present a plan to the California Public Utilities Commission (CPUC) for a review of quality assurance processes associated with the inspection of new girth welds on PG&E gas transmission pipelines.
"We're committed to becoming the safest and most reliable gas system in the country. We want to ensure that each and every step in our quality control processes is the best it can possibly be, and we want the public to have confidence that is the case. Anywhere there are problems, we want to find them and fix them," said Nick Stavropoulos, executive vice president of PG&E gas operations.
In March 2013, a PG&E inspector conducted an unannounced inspection of a job site where a third-party contractor was performing a radiographic assessment – a technique similar to an X-ray – of a girth weld on a PG&E gas transmission line in Brentwood, Calif. The PG&E inspector determined that the contractor was not performing the assessment in compliance with standard procedures for radiographic assessment of welds.
Current standards typically require three radiographic images of each weld before a pipeline is put into service. In this case, PG&E found that a contractor was creating two, rather than three, exposures. In high population areas, nearly all welds must be inspected using techniques including radiographic assessment. In lower population density areas, 10 to 15 percent of the welds must be inspected in such a manner.
As a result of its inspection, PG&E immediately removed the contractor from the project and conducted an in-depth examination of records and a sample of welds. To date, the company has identified approximately 490 radiographic images from the contractor that did not comply with the code requirements. PG&E has not identified any safety issues or issues with the integrity of any girth welds on the Brentwood project and has no evidence of any safety issues with any other girth welds. All issues were resolved and the pipeline was approved by the CPUC for entry into service.
The CPUC issued a citation because the non-compliant radiographic images constituted a violation of required standards, as identified by PG&E.
PG&E will respond with a quality assurance plan to the CPUC that addresses the work of all firms it has retained for radiographic testing as well as other measures outlined by the Commission, both to ensure public safety and public confidence in the quality control process.
Ensuring Public Safety
Radiographic testing was introduced at PG&E in the 1960s as a third layer of quality assurance consistent with industry requirements. Girth welds on pipes installed before that time have not undergone radiographic assessment. The primary control process then and now is the hiring of specially trained and certified welders. Secondarily, the work is subject to immediate, onsite visual inspection by master welding inspectors.
In 2012, the CPUC conducted an investigation into the quality of PG&E's welding program in response to allegations of substandard welding on gas transmission pipeline-related projects. The investigation included field excavations, document review and witness interviews. The CPUC issued a report in September 2012 that found no evidence of substandard welding work.
In addition to radiographic assessment, PG&E has a comprehensive integrity management program, which includes hydrostatic testing and inline inspections to ensure pipeline safety throughout the system.
"We're managing our pipeline safety work 24 hours a day from our new, state-of-the-art gas control center in San Ramon where we've centralized both distribution and transmission operations," said Stavropoulos. "The control center's advanced technologies combined with enhancements including more than 100 new automated shutoff valves across our system, allows us to respond more quickly and more effectively in the event of an incident."