Testing methods under scrutiny in San Bruno blast hearings 

The third and final day of pipeline safety hearings opened Thursday morning with a discussion about how they should best be tested.

The pipeline that exploded in San Bruno on Sept. 9 had been tested only with a method that could not have possibly detected the pipe’s fatal flaws, and regulators are examining whether more rigorous testing methods should be required on more of the large, high-pressure lines that run under neighborhoods in every city in America.

The testing method used on the San Bruno pipeline is called direct assessment, and it largely entails flying over or walking along a pipeline to see if there are any obvious signs of leaks, and in some cases sending an electrical current through the ground to try to detect corrosion.

But corrosion was not the problem with that pipeline: Instead, investigators have revealed that the pipeline was not adequately welded. That flaw that could only have been detected through in-line inspection, which involves running devices called pigs through the pipe to examine its inside, or with a pressure test, which checks the strength of the pipeline by filling it with liquid or gas far above the recommended pressure, and checking if it ruptures anywhere.

The pros and cons of the testing methods were discussed by panel members, including engineers from the federal Pipeline and Hazardous Material Safety Administration and from the gas and pipeline industries.  

At one point early in the hearing, National Transportation Safety Board researcher Frank Zakar asked Geoff Foreman, an industry engineer from General Electric, if in-line inspection would have caught the problem in the San Bruno, and Foreman affirmed that there is such a tool that would catch it.

Some experts have pushed PG&E to do less of the flimsier direct-assessment testing and more pressure testing or hydrotesting, but PG&E has said it would be extraordinarily expensive.

Representatives from the industry group American Gas Association attacked hydrotesting from another direction, saying it only catches the weakest link in a pipeline, but other portions of the pipe that are also weak — but aren’t the first to break — aren’t discovered. Further, pressurizing a pipeline far above its maximum allowable pressure, possibly exacerbates cracks or other problems, according to Charles Dippo, vice president of South Jersey Gas Company and member of AGA.

Gas industry leader Christine Sames elicited a reaction from San Bruno City Manager Connie Jackson by repeatedly describing the incident as an “anomaly.”

Jackson said that describing the tragedy as an anomaly raises fears that the industry won’t be as proactive as it should be about preventing more such accidents.


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