Aluminum alloys 3003, 3004, and 5050 were evaluated for desalination applications by means of their anodic polarization curves determined in 1X synthetic sea water at 25 C (77 F) to 150 C (302 F). Pitting performance was established from the relative values of the corrosion potential and the breakdown and protection potentials, and general corrosion rates were calculated from corrosion currents determined by the slop-intercept method. Pitting is not anticipated for 3003 and 3004 alloys at temperatures to 150 C and for 5050 alloy to 125 C (257 F). General corrosion rates for these alloys were less than 1 mpy.

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Aluminum alloys 1100, 3003, 5052, and 6063 were examined for their compatibility with the proposed working fluids for Ocean Thermal Energy Conversion (OTEC), anhydrous ammonia, Freon 22 and propane, and mixtures of these with sea water. Such mixtures would occur if leaks develop in evaporator or condenser heat exchangers. These aluminum alloys are compatible with the anhydrous working fluids. In ammonia-sea water solutions only limited general corrosion is found in 0-30% ammonia, no corrosion in 30-90% ammonia, and "self limiting" pits in 90-100% ammonia so rapid deterioration of the exchangers would not occur. No corrosion was observed in sea water saturated with Freon 22 or propane. No differences in alloy performance were evident in any of these tests so selection can be made on the basis of compatibility with sea water. A review of the available literature indicates that 5052 shows the best performance in surface sea water followed by 1100, 3003 and then 6063 alloy. In deep sea water only 5052 and 1100 alloys appear suitable although more data is required. In both surface and deep sea waters, alcladding offers the best protection against tube perforation; few instances of penetration into the core alloy have been observed for the alclad alloys examined in this stud.y.