Abstract
Seawater corrosion of aluminum alloys can adversely impact the lifetime and performance of aluminum Ocean Thermal Energy Conversion (OTEC) heat exchangers. Since uniform corrosion rates for the aluminum alloys being considered for use in OTEC heat exchangers are low, the primary corrosion mechanisms of concern are surface pitting and crevice corrosion at gasket interfaces. Makai Ocean Engineering has developed a system to observe pit growth in-situ using optical imaging and ultrasonic thickness measurements which allows corrosion development to be monitored over time without the removal and destruction of samples. Three aluminum alloys were chosen for testing (Al 2024, Al 6061-T651 and Al 5086- H116) in flowing (1 m/s) and near-stagnant cold, deep seawater (6 samples total) provided by the National Energy Laboratory of Hawaii Authority in Kailua-Kona, Hawaii.