Investigation and Solutions of Localized Corrosion of Copper Metallurgies in Industrial Recirculating Cooling Systems

Copper metallurgies are often chosen for heat exchanger material due to their improved heat transfer properties and nobility towards corrosion over a wide range of conditions. To prevent corrosion, it is the industrial standard to feed a nitrogen-containing molecule typically featuring an azole group. This includes the use of benzotriazole and substituted benzotriazoles. Despite the addition of these film-forming chemistries, there are environmental conditions that promote significant localized corrosion on the copper alloy surfaces leading to dealloying of the base metal. If an open recirculating system has elevated chlorides, residual bleach levels, and flow rates, accelerated localized corrosion can be found despite treatment. This corrosion mechanism will be investigated and discussed in detail using surface analysis techniques. Laboratory and field trial results utilizing Engineered Copper Passivation (ECP) technology will highlight the ability to provide performance improvements under these stressed conditions where standard commercial azoles underperform.