General Electric’s in-line inspection tech keeps pipelines safe
Ultrasound techniques borrowed from the medical field probe stretches of old pipe
Geoff Foreman is blunt about the risk he’s spent his 32-year career taming. “What we don’t want is pipelines exploding all over the place and people getting killed.
“My boss calls me the pipeline doctor,” he grins. But his informal title is no joke. As global sales manager of ILI, short for in-line inspection, with General Electric, he runs an industrial safety application of medical imaging equipment, which the technology giant normally supplies to hospitals and physicians.
Thirteen years after an inquiry by the National Energy Board blamed 22 mysterious Canadian pipeline failures, leaks, explosions and fires between 1977 and 1996 on an invisible form of metal fatigue, Foreman and GE have developed a method of detecting the subtle plague with a mobile ultrasound machine. The NEB has kept tabs on the system’s refinement and trusts it enough to have authorized its use as an essential first step in installing the Keystone Pipeline now nearing completion from Hardisty in central Alberta to southern Illinois and northern Oklahoma.
The northern core of the $5.2-billion project, built by TransCanada Corp. and ConocoPhillips Co. to ship about 500,000 barrels per day of oil sands production to the U.S., is a natural candidate to come down with the dangerous weakness described by the NEB’s 1996 inquiry report. The hazard, known as stress corrosion cracking or SCC for short, affects aging pipelines. The Canadian leg in Keystone is a conversion into oil service of 864 kilometers of pipe that TransCanada first laid 51 years ago to deliver natural gas across Alberta, Saskatchewan and Manitoba.
The NEB let the project go ahead on the condition that ultrasound inspections of the old line be performed twice, once before the conversion to oil traffic and then again after its first year in its new role. The job uses a $7-million “smart pig,” a submarine-like robot about five meters long, crammed full of instruments, sensors and computer hardware.
“It’s like 30 MRI machines going down the pipeline at one time,” Foreman says. Ultrasound generators fire shots into the steel walls at an astronomical rate of 13,000 per second, with 540 sensors spaced four millimeters apart receiving the return signals and computers doing preliminary sorting for hints of weak spots.
The machine fits inside the 85-centimeter (34-inch) diameter Keystone pipe as precisely as a piston in a motor. The line’s cargo of high-pressure gas pushes the unit along at a brisk pace of about one meter per second. An immense digital mural of the walls, with information content measured in gigabytes, is generated by sampling the steel’s condition in microscopic detail every two to three millimeters along the line’s entire length, which in the case of Keystone’s Canadian leg about equals the distance from Paris to Berlin. Specialists pore over the computer portrait’s mathematical data for early warning signs of SCC spots, which are dug up and repaired or replaced.
At NEB hearings on Keystone’s construction application, project engineers confirmed the old pipe in its Canadian leg is prone to stress corrosion cracking. Traditional safety checking – which uses hydrostatic testing that drains oil and gas out of pipe then pumps in water at rising pressure until it springs leaks – was admitted to be “ineffective.”
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