Alyeska Installs Structural Sleeves

Alyeska Pipeline has installed two 4-foot steel bands (sleeves) on the outside of the pipeline to reinforce two areas of pipe impacted by corrosion. The corrosion is near pipeline welds and was detected by instrumented “pigs” sent through the pipeline to check for external corrosion. Some pipe settlement had occurred in the area causing the insulating jacket around the pipe to crack. This allowed water to seep underneath the protective tape around the welds. The sleeves completely encircle the pipe to reinforce pipe strength. Alyeska has been monitoring this section of pipe for approximately four years. Data indicated that corrosion in this area had increased and the location was put on the list of sites to be inspected.

The sleeves were installed at pipeline Mile Post 652, near Sourdough along the Richardson Highway. Mile Post 652 is a specially buried and refrigerated section where the pipeline dips below ground to allow animals to cross the pipeline right of way.

This site is the next to the last to be excavated of the 10 that were identified for inspection this year. Of the nine inspected, only the MP652 location needed major maintenance and repair work. The other eight locations required minor maintenance which included recoating the pipe.

These ten areas were selected from the data received from the instrumented pigs that were run through pipeline last year. This special instrumentation pig ultrasonically tests the wall thickness of the pipe to determine if corrosion is present. After analyzing the data, certain areas are identified each year for excavation and inspection.

The corrosion inspections began in February and are expected to continue through August. Some 30 workers will complete the $4.5 million project.

Summer Tank Maintenance Begins

Alyeska Pipeline took one of the crude storage tanks at the Valdez Marine Terminal out of service last week for maintenance. The 500,000 barrel tank will be drained, cleaned, inspected and re-coated before being returned to service. A second storage tank is being prepared to be taken out of service for maintenance as well.

The crude storage tanks along the Trans Alaska Pipeline System must be inspected every 5 to 10 years. There are 18 crude storage tanks at the Valdez Marine Terminal.

The two crude tanks will have new bottoms and Cathodic Protection Systems installed. A third tank in the Ballast Water Treatment System will be cleaned, inspected, repaired, re-coated internally and re-serviced this summer as well.

Pipeline Reliability

Pipeline throughput for April 1999 totaled 32,461,000 barrels, with a daily average of 1.08 million barrels per day. Pipeline throughput for the year to date is 137,999,000 barrels, averaging 1.15 million barrels per day. Pipeline reliability for April was 99.80 percent, making the year to date reliability 99.86 percent.

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