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Update on gas pipeline testing near campus

 

Just before Thanksgiving, PG&E work crews finished the hydrostatic pressure testing of gas transmission pipeline 132 near the Stanford campus. Two sections of pipe, called T-30 and T-31, were tested to more than 1.5 times their maximum allowable operating pressure. In the run up to the final test, both pipe sections experienced problems. However, repairs were made and the pipe has now met the pressure testing requirements.

Preliminary testing of section T-30 – which runs from Alma Street in Palo Alto along Page Mill Road to Junipero Serra Boulevard, then across a corner of the golf course, across Alpine Road, along Stanford Hills to Sand Hill Road and Branner Drive in Menlo Park – found a small corrosion problem near Hanover Street on Page Mill Road.

According to PG&E, the corrosion was the result of deterioration of the protective coating on the pipe that caused a small hole to develop. Work crews uncovered the pipe and repaired it by welding a protective sleeve around the affected section, then putting new protective coating on it. Following this repair, the pipe section passed the test.

The problem with section T-31 (from the intersection of Sand Hill Road and Branner, north to Interstate 280) was caused by a damaged section of pipe, which failed during initial pressure testing. This failed section was along I-280 near Farm Hill Boulevard near Woodside/Redwood City. Water that was used for testing spilled out onto the highway and prompted a partial road closure. The failed portion of pipe was cut out and a new section welded in. Following this work, the pipe section passed the test. It is not known how or when the pipe had been damaged.

"The discovery of the problems in these two tests shows the importance of this testing in proving the safety of the gas pipeline system," said Richard Bitting, associate director of power systems in the Stanford office of Land, Buildings and Real Estate.

Testing of these pipe sections was mandated by the California Public Utilities Commission when PG&E was unable to locate records to show that the pipes had ever been tested. PG&E must complete testing of all undocumented sections of line 132 (from Milpitas to San Francisco) before the utility can return the pipe to normal service. Until then, the pipe must be operated at reduced pressure. PG&E has not completed all testing, so sections returned to service, including those near Stanford, will continue to operate at reduced pressure during the winter heating season.