Internal Corrosion Monitoring of Pipelines Using Electrochemical Techniques: A Comprehensive Review

Corrosion monitoring plays a determining role in corrosion management in industries, particularly oil and gas systems. Corrosion’s effective monitoring could be achieved through the properly selected monitoring methods, using suitable reassessment intervals as well as application of generated data. When carried out properly, corrosion monitoring can also be served as an early warning system before the onset of corrosion-associated failures. This paper provides a literature review of pipelines’ internal corrosion using electrochemical technique. Several electrochemical techniques namely electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), galvanic sensors, electrochemical noise (ECN), harmonic distortion analysis (HDA) and wire beam electrode (WBE) have been discussed in this review; as well as examples of exploiting these techniques have been presented. The main focus of this paper is reviewing field applications of mentioned techniques rather than laboratory experiments. The same trends can be exhibited through the corrosion rates determined by ECN, LPR, and EIS. Studies have implied that ECN can be a very powerful tool for monitoring corrosion rate and corrosion mechanism. LPR has been mainly utilized for water pipelines or those that have at least 30% free water. HDA has been rarely used due to the complexity of interpretation. Developed galvanic sensor system cannot numerically express the corrosion rate, but it can only provide the information about the presence of corrosion. Reliable EIS measurements could not be obtained with regularity in operating oil and gas pipelines but there some field cases of this technique has been discussed. For studying pitting tendency, WBE is a better and more accurate technique than traditional cyclic potentiodynamic polarization method. Application of potentiodynamic testing in the field is primarily limited to inhibitor evaluations. Results revealed that corrosion rate obtained by using WBE technique has good correlation with other techniques. There are numerous references, which would be very helpful in finding the details of each above-described technique. Finally many case studies for the application of electrochemical techniques in oil and gas pipelines have been gathered and tabulated as a guideline for target users which by comparing the capability and inability of each method can select the best tailored techniques for intended se-rvice.