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PG&E gas line ruptures during pressure test

October 26, 2011

A major PG&E gas transmission line ruptured during a pressure test Monday south of Bakersfield as the utility was planning to boost gas levels on the pipeline to meet winter demand. [SF Chronicle]

The 34-inch transmission line that runs from the Arizona border to Milpitas failed during a spike test at 9 a.m., blowing a crater in an alfalfa field near the Kern County town of Weedpatch, PG&E officials said.

The pipe, known as Line 300B, failed because of a tear in a longitudinal seam – the same type of failure that caused the Sept. 9, 2010, explosion of a transmission pipeline in San Bruno that killed eight people, destroyed 38 homes and damaged 70 more.

Nick Stavropoulos, executive vice president of PG&E’s gas division, said the company did not yet know what caused Monday’s failure. The line ruptured at what is known as a double submerged arc weld, a type that Stavropoulos said is highly reliable if done correctly. The San Bruno line failed because of a seam weld that was only half as thick as the pipe itself.

At the time of the rupture, workers were trying to increase water pressure on the line to 1,040 pounds per square inch. When the pressure reached 998 pounds, a 4-foot-long portion of the longitudinal seam ruptured, creating an almond-shaped hole in the pipe and blowing a sizable crater in a farmer’s field.

Monday’s failure was the only one so far among 6o pressure tests performed on 120 miles of line since the San Bruno explosion.


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I’m glad it was only a test this time.


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Whoa, the company did realize that pressure testing would in some areas actually CREATE A PUBLIC HAZARD!!!


From their website:


Gas Pipeline Replacement Program

Commitment to Reliable Natural Gas Service

In the months ahead, PG&E will replace the gas lines in several neighborhoods throughout its service area. In San Francisco, alone, the program will replace approximately 270 miles of pipeline by the end of 2014.


This will include the pipe in the street and the pipe that runs from the street to various buildings and homes. It may also require the relocation of gas meters. We know this process is inconvenient, but we are asking for your cooperation and understanding.


This work is part of our extensive Gas Pipeline Replacement Program to improve gas service to our customers. We are replacing them with modern new piping that is more resistant to corrosion and earth movement. Our goal is to have a more reliable system with less maintenance and lower energy costs. The relocation of some gas meters may be required under current California Public Utilities Commission (CPUC) requirements and or local codes and ordinances, and is based on today’s safety considerations.


This project allows PG&E to meet a commitment to our customers to provide safe, reliable service. The Gas Pipeline Replacement Program (GPRP) is by agreement between our company and the CPUC.


The pipe replacement priorities are based on age and pipe leakage history, so the highest priority pipe will be replaced first.


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Now PiGG&E’s lawyers can argue that testing creates a public hazard.


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OOPS!


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