Effectiveness of cathodic protection of UNS N04400 heat exchanger tubes for sea water service

A detailed laboratory study was performed to assess the use of carbon steel sacrificial anodes to galvanically protect UNS N04400 nickel alloy heat exchanger tubes in sea water applications. Several parameters were investigated: the potential-time relationship of uncoupled and coupled steel-N04400, the current-time relationship of the coupled alloys, the effect of a two sacrificial anode system, the effect of water path length, and the effect of new and used N04400 alloy tubes. Data analysis indicated that the application of sacrificial cathodic protection to N04400 heat exchanger tubes in sea water applications will prevent pitting corrosion and thus prolong tube service life.