In the Field
Valves Focus of 2006 Pipeline Maintenance Shutdown

During last summer's scheduled pipeline shutdown, Alyeska discovered that Check Valve 109 (CV109) did not meet internal performance standards. A risk assessment was conducted and it was determined that the valve—located in an environmentally sensitive area south of Glennallen—should be replaced.

The 2006 maintenance shutdown started at 6 a.m. on Saturday, July 22, and the pipeline was restarted at 1:32 p.m. the following day. Although the maintenance was scheduled to last 36 hours, most of the work was completed 4.5 hours ahead of schedule.

“That we were able to finish ahead of our anticipated restart goal is a direct result of their focus on safety and excellent pre-planning,” Jim F. Johnson, Pipeline Vice President said.

Work crews spent many weeks preparing for the maintenance and repair project. Over 100 TAPS employees were involved in replacing CV109. At the same time, additional crew completed other maintenance projects along the pipeline, including the installation of a check valve at Pump Station 10. CV 109 is one of 82 check valves located along the 800-mile-long pipeline. The valves are designed to be held open by flowing oil and to close automatically when oil flow stops or is reversed.

“The credit really goes out to everyone working in the field, at the terminal, and throughout the company who helped plan and execute the work,” Johnson added.

Installing the check valve at Pump Station 10 included a procedure known as "hot tapping": drilling a hole into the pipeline through a split-tee to provide access points for stopple installation. The pipeline was sealed by inserting stopples into the 48-inch diameter pipeline through the hot tap on each side of the valve, plugging and isolating the pipeline both upstream and downstream of the check valve.