Evaluation of Galvanic Corrosion Failure of Coupled Dissimilar Steel Pipes for Borehole Application

Abstract

In this work, the corrosion failure analysis of two connected dissimilar pipes obtained from a borehole site was investigated. The chemical composition and microstructure of the pipes were obtained using XRF and optical microscopy respectively. The corrosion potential (Ecor) and corrosion current (Icor) of the two pipes were determined using the Tafel polarization curve in water obtained from the borehole. In addition, SEM and EDX of the inside and outside of the pipes were conducted. From the results, it shows that the carbon contents of the two pipes were different. Potentiodynamic polarization results revealed that Steel pipe A exhibited a more negative corrosion potential (-0.75 to -0.55 V vs SCE) and higher corrosion current compared to Steel pipe B (-0.55 to -0.35 V vs SCE), potentially leading to galvanic cell formation when coupled. The SEM and EDX further show that one of the pipes has undergone more oxidation than the other. This shows that coupling two dissimilar steel pipes for borehole application can lead to corrosion failure.