Point Thompson back pressure system down

Petroleum News Alaska Staff

Alyeska Pipeline Service Co. said Feb. 2 that the backpressure control system for Thompson Pass was shut down Jan. 31 and will be out of service for 10-14 days for inspection and repair.

Jan. 30, pieces of a pipeline cleaning pig arrived at the Valdez Marine Terminal. The transmitter/locator for the pig was detected in the backpressure piping in front of one of the backpressure valves; locations of other pig components have not been determined.

Alyeska said technicians will inspect the pig trap, isolate the backpressure system and clean and inspect the backpressure piping to determine if other components of the pig have traveled into the backpressure piping and are inhibiting its proper operation.

The backpressure control system was installed in 1997 to eliminate vibrations in the pipeline on the south slope of Thompson Pass.

Alyeska said that vibrations experienced while the system is off-line do not create a risk to pipeline and that residents near the pipeline in this area have been notified of the situation and the repair schedule.

The Joint Pipeline Office said Feb. 17 that it was continuing to oversee Alyeska’s investigation of the damage to the system and has asked Alyeska to provide: a plan and schedule for repair; briefings on the blockage and cause of damage to the cleaning pig; and an estimate of how long the backpressure system could remain off line without a danger to the integrity of the pipeline.