Alyeska responds to corrosion concerns

An internet blog raised questions regarding Alyeska's corrosion control and prevention program. There were several points that warrant clarification because they misrepresent the facts about the company's comprehensive approach to integrity management on the 800-mile Trans Alaska Pipeline System.

Alyeska has a robust integrity management program that involves preventative measures, monitoring, investigation and mitigation. The program is regulated by the Joint Pipeline Office and the Department of Transportation, Pipeline Hazardous Materials Safety Administration, and Alyeska’s criteria for action are generally more aggressive than required by DOT. For example, Alyeska performs In Line Inspection tool (smart pig) runs every three years, although DOT regulations require inspections every five years. Alyeska has a history of pigging more frequently if the data indicates a need.

Alyeska monitors both internal and external corrosion and tracks the 319 anomalies addressed in the authors’ blog. Engineers study the characteristics of each anomaly and its rate of change over time and use this data to determine when to inspect and mitigate. As dictated by 49 CFR 195.452, Alyeska mitigates corrosion in high consequence areas (HCA) as well as non-HCA areas.  Regulations require Alyeska to inspect anomalies when there is wall-loss of 50 percent or greater, yet Alyeska applies a more stringent investigation threshold of 40 percent wall loss. All anomalies on TAPS with a reported wall loss greater than 40% have been investigated and repaired.

The author incorrectly cites a loss of 47 percent wall thickness at one location on TAPS. The area in question involves a location where there is a change in pipe wall thickness. The true wall loss for this anomaly is 33 percent and the area is scheduled for inspection in 2009.