July 19, 2006 — A device that uses guided wave technology to inspect heat exchanger tubes has received a 2006 R&D 100 Award. R&D Magazine selected Southwest Research Institute's® (SwRI®) MsS® (Magnetostrictive Sensor) Heat Exchanger Probe as one of the 100 most significant technological achievements of the past year.
Heat exchangers are essential to the operation of many systems in industry, including processing plants and electric power generation plants. Because of their vital importance to plant operation, heat exchangers are inspected and maintained during regular service outage.
Conventional inspection techniques of heat exchanger tubes, such as ultrasonic and eddy current, examine one local area at a time and therefore a scan of the entire tube is required. Because there are several hundred — or in some cases thousands — of tubes in a heat exchanger, and conventional inspection is slow, only a small fraction of the tubes is inspected.
"Our device represents a significant improvement over current inspection techniques," said Dr. Glenn Light, director of the Sensor Systems and NDE Technology Department in SwRI's Applied Physics Division. "The SwRI-developed MsS Heat Exchanger Probe allows fast inspection of the entire length of a tube, generally within 20 to 30 seconds."
The hand-held probe generates and detects torsional guided waves which fill the entire tube wall. These waves also have the advantage that they don't couple into liquid on the tube wall like other waves. A short pulse of the waves generated by the probe is mechanically coupled to the tube under inspection and propagates along the length of the tube. When the transmitted wave encounters geometric anomalies such as corrosion and cracks in the tube wall, a part of the wave is reflected and travels back to the probe where the signal is detected. At the same time, the transmitted pulse keeps propagating toward the far end of the tube, producing reflected signals whenever it encounters anomalies.
"Using our device, 100 percent of the tubes can be surveyed faster than conventional methods can sample a smaller number of tubes, thereby identifying any potential problems," Light said. "Our product streamlines inspection significantly and helps industry maintain heat exchanger reliability more cost-effectively."
SwRI holds U.S. Patent No. 7,019,520, "Method and System for Torsional Wave Inspection of Heat Exchanger Tubes," for the MsS Heat Exchanger Probe. Inventors are Staff Scientist Dr. Hegeon Kwun, Staff Engineer James F. Crane and Senior Research Engineer Dr. Sang Y. Kim, all of SwRI's Sensor Systems and NDE Technology Department.
SwRI has won 30 R&D 100 Awards since 1971. This year's awards will be presented October 19, 2006, in Chicago.
For more information contact Deborah S. Deffenbaugh at (210) 522-2046, Communications Department, PO Drawer 28510, San Antonio, TX 78228-0510.