Effect of pollutants on corrosion of copper alloys in sea water: Part 2: Sulphide and chlorine

Abstract

Sea water corrosion tests of five copper alloy heat exchanger materials were undertaken to examine the effects of sulphide, commonly present as a pollutant in sea water, on their corrosion behaviour, particularly in the presence of chlorine. Corrosion, particularly impingement attack, increased with increasing sulphide level, 90Cu−10Ni showing the smallest amount of corrosion. When sulphide plus 0·25 ppm Cl₂ was present, all the alloys except 66Cu−30Ni−2Fe−2Mn suffered less attack than with sulphide alone. However, when sulphide plus 0·25 ppm Cl₂ was present, all the alloys except 70Cu−30Ni suffered greater attack than with sulphide alone. The severity of attack in the presence of chlorine plus sulphide is thought to depend on the excess chlorine available after reaction with the sulphide. The corrosion resistance ranking of the alloys under heat treatment conditions in the presence of sulphide appears to be different to that at ambient temperature.