Further Development of Probe for Flow-Accelerated Corrosion Monitoring in Power-plant Feedwater Systems

Abstract

Development of an electrical resistance probe for monitoring Flow-Accelerated Corrosion (FAC) has been ongoing for decades. The accuracy of wall-thickness determinations has been demonstrated, problems of the voltage measuring technique giving data fluctuation have been found. This lowers the sensitivity of corrosion measurement. A voltage measuring technique, three-point delta, was investigated and compared with a traditional resistance averaging method on two probes manufactured from two different carbon steels; typeA106B (0.019%Cr) and STPT480 (0.001%Cr). Experiments were performed at various temperature from 80°C to 220°C. Results show the three-point delta provided better R² on the linear relation between resistance and temperature. The scattering of data, for example of A106Bat ~140°C, was significantly reduced from ~2.35 μΩ (via the normal average method) to ~0.7 μΩ.