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US pipeline operator seeks waiver for faulty storage tank

20th September 2012

Alaska’s environmental watchdog orders Alyeska to suspend storage tank, pipeline operator acknowledges technical deficiencies and seeks new waiver

US pipeline operator seeks waiver for faulty storage tank
CP controls the corrosion of a metal surface by means of a “sacrificial” metal which protects the former and acts as the anode of the electrochemical cell

Alaska-based pipeline company Alyeska Pipeline Service Co. is looking to delay an inspection by an environmental agency on one of its crude oil storage tanks, it emerged on Wednesday, after the agency pointed out technical faults in the system.

Alaska’s Department of Environmental Conservation (DEC) in May withdrew an inspection waiver initially awarded to Alyeska in February. The waiver postponed an internal inspection of Alyeska’s Tank 5 at the Valdez Marine Terminal by two years and increased the time between such inspections from 10 to 12 years.

The environmental agency withdrew the waiver on the grounds that Alyeska failed to comply with conditions relating to tank corrosion control, more specifically to the correct operation of its cathodic protection (CP) system. In a letter, DEC claimed CP was working correctly only 26 per cent of the time.

CP is a technique used to control the corrosion of a metal surface by means of a “sacrificial” metal which protects the former and acts as the anode of the electrochemical cell.

As a result, DEC ordered Alyeska to suspend tank 5 have it inspected by 31 December.

The pipeline operator is now seeking to reinstate the waiver, after acknowledging in June that some technical deficiencies occurred in the tank.

Alyeska is the operator and private owner of the Trans-Alaska Pipeline System and the Valdez Marine Terminal, which comprises 18 510,000-barrel storage tanks measuring 250 feet wide and 63 feet high.

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