Internal Corrosion Detection in Pipes Using Piezoelectric Transducers

Abstract

This paper introduces a new method for internal corrosion detection in metal pipelines using an externally surface bonded (SB) piezoelectric transducer working on electromechanical impedance technique (EMI). Specifically, changes in mechanical properties of the structure is monitored by observing the changes in structural mechanical impedance obtained through the bonded piezo electric sensor thereby employing EMI technique. Through controlled incremental corrosion induced in the pipe segment considered for experimentation using accelerated corrosion tests a realistic corrosion environment was proposed. The hourly exposure to corrosion is correlated with the signatures acquired through the sensors. Sensitive parameters such as temperature and humidity were kept constant to discern changes solely due to corrosion. Through timely phased acquisition of signatures using an LCR meter, shift in conductance may be monitored. Changes in structural parameters such as stiffness, mass and damping is calibrated through conductance signature analysis. Development of corrosive products was monitored simultaneously with scanning electron microscopy (SEM). Experimental results show that good correlation exists between the obtained SEM analysis and change in structural parameters. A steady decrease in stiffness and mass was witnessed with a noticeable trend in magnitude. In essence, a simple, easy implementable method in employing EMI method to detect internal corrosion in pipelines is demonstrated.