Atmospheric corrosion in marine environments is primarily due to airborne chlorides, time of wetness,
high relative humidity, and temperature. A performance evaluation and comparison of three
commercially available coatings on steel substrates and two non-coated steel materials was conducted
at military sites near the ocean in the severely corrosive coastal environment in Okinawa Japan. Twelve
test panels (sized 10 cm. X 15 cm. X 3.125 mm.) were exposed for each of the following systems: (1)
hot dip galvanized coatings on low carbon steel, (2) zinc rich primer system on low carbon steel, (3)
phenolic system on low carbon steel, (4) uncoated AISI 410 series stainless steel, and (5) uncoated
low-carbon steel. Scribes lines were introduced into the coatings to test for undercutting, and each
system was exposed on test racks at two locations, ~150 m. and ~600 m. from the ocean, respectively.
Three panels were removed from each system, at 60-70 days intervals and evaluated with respect to
corrosion rates and coating performance, until all 120 panels had been evaluated. The results of this
short test (~ 8 months) indicated relative abilities of coating systems to protect steel and the limitations
of low chromium stainless steel alloys in coastal environments.
KEYWORDS: corrosion rates, marine environments, 410 stainless steel, phenolic coating, zincepoxy
coating, galvanized coating, weathering steel