Pacific Gas and Electric Co. to shut down San Carlos gas pipeline

Pacific Gas and Electric Co. (PG&E) has begun shutting down a natural gas pipeline in San Carlos, California, to comply with a court order, according to company officials.

A San Mateo County judge ordered PG&E to shut down the pipeline last week. The closure of the pipeline, which is known as Line 147, came after emails surfaced from an engineer questioning whether an 83 year old seam weld was safe.

The type of weld, which has been previously problematic, was not known to exist on the portion of pipeline in question, until work crews found it while making repairs, raising concerns about a repeat of the September 2010 explosion in San Bruno that killed eight people and destroyed 38 homes. 

PG&E insists that the pipeline is safe

The utility said in a statement that the pipeline shutdown would be completed "as early as Monday or Tuesday," but assured customers and city officials that the line was safe.

PG&E engineer warns of potential safety threat

City leaders asked a judge to step in after PG&E emails surfaced questioning the safety of the line.

The transmission line, which runs between Highways 280 and 101, is similar to the pipeline that exploded in San Bruno three years ago.

A Superior Court judge ordered the 20 in. transmission line shutdown "in a safe and effective manner" after San Carlos officials declared a state of emergency on Friday.

The emergency declaration came after they obtained an emailed warning by a PG&E engineer about a seam weld dating to 1929 on a transmission pipe at Brittan and Rogers avenues in San Carlos.

The presence of the old weld, discovered last November when crews went in to repair corrosion, did not appear in PG&E's records. The records, in fact, showed a more reliable type of weld at that location, according to the engineer, whose name was not released.

Could a recent hydrotest have contributed to the threat?

The engineer also expressed concern that a high-pressure water inspection of the gas line may actually have heightened the danger by making the weld weaker.

"Could the recent hydrotest (have) contributed to additional cracking on this pipe and essentially activated a threat?" he asked in his email to executives. "Are we sitting on a San Bruno situation?"

Work begins to take the line out of service for tests

PG&E officials said the 3.8 mile long pipeline could not be taken out of service without risking major disruptions to customers until work on another Peninsula gas line stretching from South San Francisco to San Jose was completed. Now that that work is done, the line can be isolated and other work, including testing and valve work, can be completed. In the meantime, utility officials said they had reduced pressure inside the pipe by 20%.

"Although this is a line that is going out of service, we want to be clear that this is a safely operating pipeline," said a spokesman for PG&E. "We're shutting the line to comply with the court's order. It's being done out of an abundance of caution."

Edited from various sources by Elizabeth Corner

Read the article online at: https://www.worldpipelines.com/business-news/07102013/pacific_gas_and_electric_co_starts_shutting_down_san_carlos_gas_pipeline_478/