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http://apnews.excite.com/article/20060812/D8JF5K980.html'Smart Pigs' Keep Oil Pipelines Clean
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Aug 12, 6:45 PM (ET)
By KRISTEN HAYS
HOUSTON (AP) - Of all the technologies available to maintain the nation's 2 million miles of pipelines, one of the most critical devices evokes images of a muddy farm animal - the pig.
Now erase the image. The earliest, primitive pipeline pigs may have squealed as they scraped wax, mineral deposits, sand or other corrosion-causing debris from the insides of the nation's energy highways, but even that similarity is long gone.
Pipeline pigs sit on the shelves at Inline Services Inc., a Houston area-based pig manufacturer and distributor, Thursday, Aug. 10, 2006 in Tomball, Texas. Propelled by pressure, oil or other contents running through the pipeline, the devices that often look like huge dumbbells dislodge debris and clean the pipe walls. The importance of so-called "pigging" leaped to center stage this past week after BP PLC shut down part of the Prudhoe Bay oil field on Alaska's North Slope, raising questions about the integrity of the country's pipelines and how more than 3,000 pipeline operators keep them running. (AP Photo/David J. Phillip)
The importance of so-called "pigging" leaped to center stage this past week after BP PLC (BP) shut down part of the Prudhoe Bay oil field on Alaska's North Slope, raising questions about the integrity of the country's pipelines and how more than 3,000 pipeline operators keep them running.
Metal, foam, plastic or gel, ranging in size from a few inches to seven feet tall and wide as a tree - or however big they have to be to fit snugly inside a pipe - some pigs are simple scrapers. Others, known as "porcupine pigs," sport scrubbing wire brushes.