Effect of pollutants on corrosion of copper alloys in sea water: Part 1: Ammonia and chlorine

Abstract

The results of sea water corrosion tests on five copper alloy heat exchanger materials are presented. The tests were undertaken to determine whether ammonia, commonly present as a pollutant in sea water, would adversely affect their corrosion behaviour. All five alloys proved more susceptible to crevice attack in the presence of ammonia when heat transfer conditions were additionally present. Crevice attack was suppressed by the addition of iron to the sea water. A second series of experiments, to examine the effect of the simultaneous presence of chlorine and ammonia in the sea water, showed that, while crevice attack was suppressed by the chlorine addition, two of the alloys became markedly more susceptible to impingement attack under these conditions. A discussion of service failures examined at BNF is presented, illustrating how the presence of ammonia can lead to failures and how such failures can be avoided.