Acquisition, visualisation and interpretation of pipeline corrosion monitoring data

Localised corrosion and coating failure occur frequently on underground metal structures such as oil and gas pipelines and water mains that are often under the effects of dynamically changing soil conditions, stray currents, coating disbondment and cathodic shielding. In order to ensure the safety and durability of these assets, there is a need for visibility and understanding of corrosion and material degradation processes occurring on these buried structures. Traditionally historical field inspection data are used as the main source of knowledge for forecasting the degradation and service lives of buried pipelines; however these data have limitations because of their lack of in-situ and site-specific localised corrosion information. In order to overcome weaknesses in conventional asset management tools, corrosion monitoring using variously designed probes/sensors has been employed as a means of acquiring in-situ and site-specific data for the early warning of structural failure and life prediction. This paper provides an overview of current status of corrosion monitoring in the pipeline industry and a brief discussion on its future prospects. Cases are described to illustrate our current approaches to, (i) monitoring and visualising passivity breakdown and localised corrosion of buried steel under the effect of dynamic anodic transients; (ii) monitoring and visualising coating disbondment under overprotection potential; and (iii) monitoring and visualising localised corrosion under a simulated pipeline coating.