PG&E used wrong tests for years after '74 rupture

[The Straight Story]

PG&E used wrong tests for years after '74 rupture

SAN FRANCISCO -- Pacific Gas and Electric Co. knew that the major natural-gas line that failed in a test near Bakersfield last week had ruptured nearly 40 years ago because of a flawed seam weld, but the company long relied on an improper inspection method for the pipeline that was not capable of finding such problems, The Chronicle has learned.

The longitudinal seam flaw found in 1974 during a test on the pipe that carries gas from the Arizona border to the Bay Area was the same defect that caused last year's deadly explosion on a transmission pipeline in San Bruno. However, as on the San Bruno line, PG&E persisted in vouching for the pipe's safety by using an inspection method that is suited mainly for finding corrosion, not bad welds.

A federal pipeline safety official said that under a pipeline safety law passed in 2002, PG&E should have been using tests designed to catch flawed welds on the Central Valley line because of the earlier rupture. Instead, the company didn't start conducting them until after the San Bruno disaster in September 2010.

It was such a test - in which the pipeline is shut down and filled with water boosted to high pressure levels - that found another flawed weld Oct. 24 on the line just west of Bakersfield.

http://articles.sfgate.com/2011-11-01/news/30348685_1_pipeline-safety-longitudinal-seam-pg-e