Localized corrosion in an electrical submergible pump (ESP)

A failure analysis was performed on bolts (Monel K-500) that serve to support and join critical components of an electrical submergible pump (ESP) located in a saline solution environment. Based on the experimental results, it can be concluded that pitting corrosion was the primary cause of failure. All fracture surfaces displayed an initial zone of intergranular fracture promoted by pitting corrosion and a propagation zone with transgranular fracture due to mechanical load. High concentrations of sulfur (S) and chlorine (Cl) were found on two corrosion product layers covering the bolt surface, revealing that an aggressive electrochemical reaction occurred in the stagnant environment. Under these layers, small pits of 10-30 mu m in depth were observed that initiated the cracking paths that eventually became complete fractures. (C) 2015 Elsevier Ltd. All rights reserved.