Validation of localised corrosion model using real time corrosion monitoring in a chemical plant

A mechanistic model was developed and applied to predict the localised corrosion of a number of alloys in a plant process stream. In order to validate the model, multi-electrode array sensors (MAS) made from type 316L stainless steel and from two Fe-Ni-Cr-Mo-W alloys, AL6XN and alloy C-276, were installed in a side loop of a process stream in the chemical plant. The pitting corrosion rates measured from the probes were consistent with the plant equipment experience. The pitting rates obtained from the long term measurements were in good agreement with the actual corrosion rates obtained from post-test surface examination of the probes. The model successfully predicted the relative ranking of the alloys in this process environment. The pitting rates measured by the probes were consistent with model predictions.