Tank Valves to be Replaced in 2000

Alyeska Pipeline Service Company is planning a project to rebuild all pressure/vacuum valves on crude oil and ballast water treatment storage tanks at the Valdez Marine Terminal. Stage one of this project involved rebuilding pressure/vacuum valves on two tanks. A total of 21 valves were rebuilt during the 1999 project season. The remaining 188 valves will be inspected and rebuilt next year.

Pressure/vacuum valves are the prevailing safety devices used by the oil industry to protect the structural integrity of a tank against over- or under-pressurization, but are not specifically designed to provide a leak-tight seal. Alyeska’s valve maintenance program has successfully protected the tanks against under- and over-pressurization; however, deterioration of some components and difficulty in obtaining spare parts for these custom-manufactured valves prompted Alyeska to expand its maintenance program to include emission minimization.

A conceptual study conducted in June addressed pressure/vacuum valve performane, inspection and maintenance procedures, emissions concerns, and functional testing methods. A cooperative effort between Alyeska and the valve manufacturer has resulted in a comprehensive maintenance program that will ensure that pressure/vacuum valves operate within their design criteria. The manufacturer assisted in the update of applicable inspection and maintenance procedures, provided field calibration procedures, developed valve repair kits, and trained Alyeska technicians to rebuild and recalibrate the valves. Based on this year’s success rebuilding valves in the field, Alyeska plans to rebuild the remaining tank pressure/vacuum valves next year at a cost of more than $1 million.