Pigs and the pipeline: Alyeska uses the Geopig to inspect the trans-Alaska oil pipeline.

• Author: Grenn, Ben

The classic children's story of The Three Little Pigs takes on an entirely different meaning when discussing pipeline inspections in Alaska.

It turns out that the one little piggy that was going to market may actually have been on the way to the oil market, helping the oil industry to inspect oil and water lines in the state. The "Geopig," the most notable and vital source used in pipeline inspection, is an ultrasonic inspection tool, which varies in size, but can weigh up to 3.2 tons. The pig has been in use since the late 1980s and has an excellent reputation among pipeline operators for its reliable corrosion detection and analysis techniques.

There are two different styles of pigs that venture down the pipeline. The first pig down the line cleans it out, while the second, "the smart pig," goes through to collect the necessary data. Sending a pig down a pipeline may sound like a strange thing, but it makes the pipeline safer and more efficient.

"These 'pigs' help us prevent and detect problems in the pipe," said Lee Monthie, Alyeska Pipeline Service Co. vice president of engineering. "Mechanical pigs clean the pipe, scraping wax buildup off the pipe walls. This makes the oil easier to pump. That wax is then put back in the system (and recycled)."

Other "smart" pigs use ultrasonic, high-resolution imaging to detect corrosion. Still others use geometry to check for stress bending in the pipe wall.

In 1988, BJ Pipeline Services introduced the patented Geopig tool. Since then the use of the state-of-the-art inertial navigation systems, integrated with Global Positioning System technology, has revolutionized pipeline mapping and Geographic Information Systems. In 1996, BJ Services introduced VECTRA, a new generation of high-resolution MFL (Magnetic Flux Leakage) pipeline inspection tools.

The United States depends on the trans-Alaska oil pipeline to deliver 17 percent of its domestic oil production. Without this vital link to North Slope oilfields, the entire nation would be affected. "We have a tremendous responsibility of keeping this oil flowing in a safe, efficient and environmentally sound manner," said Monthie, an 11-year employee with Alyeska.

LOST PIGS

Occasionally, the pigs are hard to track.

"It's sometimes like going on an Easter egg hunt when we have to go looking for a pig," said Mark Hylen, describing how a Geopig tool occasionally becomes "lost" running hundreds of miles down the trans-Alaska oil pipeline system. "Finding that...