Purpose – In this investigation, attempts were made to distinguish critical coating faults in order of repair priority in DCVG þ CIPS survey data by new proposed equation for calculating IR drop. The paper aims to discuss these issues. Design/methodology/approach – DCVG þ CIPS, XRD, EDS. Findings – A new empirical equation was developed which is able to predict the importance more precisely. Besides, the studies proved the corrosion products were mainly hematite and goethite, and the presence of Cl anions was not noticed. As a result, the corrosion attack had a form of non-uniform localized corrosion. Originality/value – The values were gathered by DCVG þ CIPS method of survey.

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