A piece of steel 10 inches in diameter -- used in the construction of the trans-Alaska pipeline system (TAPS) during the late 1970s -- was found Sunday in a valve in Valdez, the end of the 800-mile pipeline. The Threaded O-Ring (TOR) was apparently put into the pipeline during construction.
The TOR was part of the system used to test the pipeline’s integrity before oil began flowing in 1977. Alyeska Pipeline Service Co., which operates the pipeline, said Monday that the piece of steel was discovered by technicians checking on a back-pressure valve at the line's terminus in Valdez, a community of about 4,000 located on Prince William Sound in Southcentral Alaska.
The company believes the TOR was pushed more than 415 miles, from its origin south of Livengood, near pump station No. 6, by a so-called smart pig. Pigs are mechanical, maintenance and electronic tools that are inserted into and forced down the pipe, like a bullet down the barrel of a gun, to check for weak spots.
"We believe it is a top-vent that fell off sometime between 2012, and four or five months ago, when we sent the pig through the area," said Michelle Egan, spokeswoman for Alyeska Pipeline Service Co.
The area from which the pipe piece came was covered with a steel sleeve in 2012. A year earlier, Alyeska began reinforcing TORs along the pipeline, which transports oil from Prudhoe Bay Alaska, on the state’s North Slope, to Valdez -- where tanker ships fill up and take the crude to refineries in the Lower 48.
Alyeska said it has sent security and technical crews to the site where the TOR originated from -- 385 miles south of Prudhoe Bay -- to check for any problems and monitor the integrity of the covering sleeve. Another covering sleeve is likely to be placed over the area, to ensure the integrity of that part of the pipeline. Alyeska said it does not believe the work will require a shutdown of the pipeline.
“No oil has leaked, there is no problem with the line itself,” Egan said.
Contact Sean Doogan at sean(at)alaskadispatch.com