SwRI® researchers develop system for real-time monitoring of corrosion

San Antonio -- May 11, 2004 -- Engineers at Southwest Research Institute® have developed the Multielectrode Array Sensor System (MASS) for real-time monitoring of localized corrosion in structures such as bridges and aircraft and in chemical plants, power plants and refineries.

Localized corrosion is one of the most common failure modes for engineering components. Corrosion often results in high rates of metal penetration and leads to premature component failure even though much of the metal surface may not be affected.

MASS uses multiple miniature electrodes composed of materials identical to the component being tested as the sensing electrode. The electrodes are coupled together by connecting each to a common joint through independent small resistors, with each electrode simulating part of a corroding metal.

In a localized corrosion environment, anodic current flows into the more corroding electrodes and cathodic current flows out of the less or non-corroding electrodes. These currents, measured from the voltage drop across the small resistors, are used as the signals for localized corrosion.

The system also includes an SwRI-developed multi-channel, high-resolution, voltage-measuring system and its associated software. The software has a graphical user interface for specifying the configuration of the measurement, including the mapping of electrode locations. During the measurement, the current values are stored in memory and displayed numerically and graphically.

"The Multielectrode Array Sensor System can be tailored to meet the process needs of a variety of industries," said Dr. Narasi Sridhar, a program manager in SwRI's Mechanical and Materials Engineering Division and a developer of the system. "Various prototypes have been fabricated using carbon steels, stainless steels and nickel-based alloys. These prototypes have successfully measured localized corrosion taking place under a number of simulated conditions including cooling water, concentrated chloride solutions, humid air and hygroscopic salt deposits."

The versatility of the system allows it to be a viable instrument to detect corrosion in such diverse structures as aircraft, natural gas pipelines, refineries, military equipment in corrosive environments, and offshore structures.

"The Multielectrode Array Sensor System is a significant improvement over existing technologies because the system is a sensitive indicator of localized corrosion, can detect formation of corrosive electrolytes and can measure localized corrosion rates. Additionally, it provides a real-time indication of localized corrosion," Sridhar said.

For more information about the Multielectrode Array Sensor System, visit www.corrosion.swri.org.

For more information, contact Deborah S. Deffenbaugh, Communications Department, (210) 522-2046, Southwest Research Institute, PO Drawer 28510, San Antonio, TX 78228-0510.

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