A Combined Approach for High-Resolution Corrosion Monitoring and Temperature Compensation Using Ultrasound

A novel approach for combined corrosion monitoring and temperature compensation (CMTC) using permanently installed immersion ultrasound probes with a well-defined standoff is presented. Combining subsample delay estimation with knowledge of how the sound speed in the immersion fluid and the steel varies with temperature enables us to simultaneously estimate the temperature variations and the changes in wall thickness using a linearized maximum-likelihood estimator (MLE). The results show that submicrometer changes in the wall thickness are detected and that the corrosion rates are predicted in good accordance with theory, also in the presence of temperature variations.