A Study on Corrosion of Paint-Coated Steel With Defects in Marine Environment

Abstract

This paper presents the results of the laboratory investigations on the corrosion of paint-coated steel plates with defects under laboratory conditions of simulated marine environment and in the field. First, experimental qualitative evidence showing significant similarity of the polarization behavior between divided, which were used for measurement of each potential and macrocell current, and undivided steel plates was established. Macrocell and microcell corrosion were then monitored in paint-coated steel plates with defects under different exposure situations and temperatures. Lastly, corrosion rates in an existing paint coated steel structure in the field were estimated. Results show that values of electro-chemical measurements in divided steel plates are almost the same and showed the same trend as the undivided steel plate. Macrocell corrosion occurred between the painted part and the defect part of the steel plates. The exposure condition where high oxygen supply and high temperature exist, provided the most severe environment for corrosion of paint coated steel with defect. Moreover, corrosion rates in an existing steel structure in the field were successfully estimated.

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