Principles and issues in structural health monitoring using corrosion sensorsM. YJ Tan*Institute for Frontier Materials and School of EngineeringDeakin University Victoria 3220 Australia*Presenting author mike.tan@deakin.edu.auSUMMARY: An approach to achieving the ambitious goal of cost effectively extending the safe operation life of critical infrastructures such as buried pipelines to for instance 100 years is the application of structural health monitoring sensors and life prediction tools. Various corrosion monitoring sensors and life prediction tools have been developed and reported in the literature; however their ability of providing in-situ condition monitoring and their performance and limitation in detecting localised forms of corrosion are often not sufficiently evaluated. This paper discuss basic principles of structural health monitoring using sensors and critical issues related to the suitability advantages and limitations of major types of corrosion sensors with particular focus on sensors used in high resistivity media such as soil [1]. A basic principle that underpins the use of sensors to monitor localised corrosion and coating failure has been presented with buried pipeline as an example. Localised corrosion and coating failure are not an accidental occurrence it occurs as the result of fundamental thermodynamic instability of a metal exposed to a specific environment. Therefore corrosion and coating disbondment occurring on a buried pipeline will also occur on a sensor made of the same material and buried in the same pipeline condition. Although the exact location of localised corrosion or coating disbondment could be difficult to pinpoint along the length of a buried pipeline the ‘worst-case scenario’ and high risk pipeline sections and sites are predictable. Sensors can be embedded at these strategic sites to collect data that contain ‘predictor features’ signifying the occurrence of localised corrosion CP failure coating disbondment and degradation [2-6]. Information from these sensors will enable pipeline owners to prioritise site survey and inspection operations and to develop maintenance strategy to manage aged pipelines rather than replace them. The concept of in-situ monitoring and site-specific warning of pipeline corrosion is illustrated by a case of monitoring localised corrosion under disbonded coatings using an electrochemically integrated multi-electrode based new corrosion monitoring probe [2-4].REFERENCESTan YJ Experimental methods designed for measuring corrosion in highly resistive and inhomogeneous media Corrosion Science 53 (2011) 1145.2. F. Varela M. Y.J. Tan and M. Forsyth Electrochemical method for studying localized corrosion beneath disbonded coatings under cathodic protection Journal of the Electrochemical Society 162(10):C515-C527 01 Jan 20153. F. Varela M. Y.J. Tan and M. Forsyth An electrochemical method for measuring localized corrosion under cathodic protection. ECS Electrochemistry Letters 4(1):C1-C4 014. Varela F. Tan M. Y. J. and Forsyth M. A new electrochemical method for measuring localized corrosion under cathodic protection Elechrochemical Socialty Letters 4 C1 (2015).5. Y Huo M. YJ Tan and M Forsyth Visualising dynamic passivation and localised corrosion processes occurring on buried steel surfaces under the effect of anodic transients Electrochemistry Communications (Available online 24 February 2016)6. F. Mahdavi M. Y.J. Tan and M. Forsyth Communication - An Approach to Measuring Local Electrochemical Impedance for Monitoring Cathodic Disbondment of Coatings Journal of The Electrochemical Society 163 C228-C231 (13 February 2016)

Keywords: Structural health monitoring, corrosion monitoring, corrosion sensor, pipeline corrosion