Southwest Research Institute^® (SwRI^®) News

SwRI-developed technology will more reliably alert pipeline operators to mechanical damage before pipelines fail

San Antonio, Texas -- August 16, 2002 -- Southwest Research Institute^® (SwRI^®) has developed a noninvasive technology to better detect defects in oil and gas pipelines before they can cause potentially dangerous pipeline failures.

Nonlinear harmonic (NLH) sensor technology developed at SwRI is being investigated through sponsorship from the U.S. Department of Transportation's (USDOT) Office of Pipeline Safety in response to concerns over shortcomings of existing in-line inspection methods.

Pipelines, typically buried three to five feet beneath the ground, carry natural gas, gasoline, crude oil, and other products from their sources in the nation's oil and gas fields to refiners and consumers – sometimes passing beneath the nation's population centers.

"Not until there is an anomaly in the line's operation does the average citizen become aware of a pipeline's presence," said Al Crouch, a staff engineer in SwRI's Applied Physics Division.

The leading cause of pipeline incidents is outside force, such as excavation from construction equipment, according to USDOT. In 2001, there were 35 transmission pipeline incidents, resulting in $14 million in damages, according to USDOT records.

While some incidents cause an immediate rupture of the line, others leave a gouge that may cause a delayed failure.

NLH sensors are deployed against the inside surface of a pipe by an in-line inspection device called a "smart pig," which is propelled by the flow of product through a pipeline. The sensor arrangement on the pig provides 360-degree coverage of the inside surface of the pipe.

Unlike conventional in-line inspection methods, NLH sensors detect stresses and strains generated on the inside of the pipe by outside force. NLH contour plots show not only the presence of a defect but also indicate its length and width.

"These multiple capabilities had not previously been possible with any commercially available in-line inspection tools," said Dr. Graham Chell, Institute scientist in SwRI's Materials Engineering Department.

A Houston-based inspection vendor is tailoring NLH sensors developed by SwRI for commercial use in a U.S. Department of Energy project funded by the National Energy Technology Laboratory.

For further information, contact Al Crouch, at (210) 522-3157 or acrouch@swri.org or Dr. Graham Chell at (210) 522 5427 or graham.chell@swri.org.

For more information, contact Joe Fohn, (210) 522-4630, Fax (210) 522-3547, Communications Department, Southwest Research Institute®, PO Drawer 28510, San Antonio, Texas, 78228-0510.