1992 Volume 41 Issue 2 Pages 89-95
Marine structure models were constructed at Fukuyama Bay in 1974 to study corrosion protection systems over a long term. The models consisted of full scale pipes which were protected by various heavy-duty coatings such as paints, linings, concrete and noble metal wrappings. Field investigations of paint adhesion, electric resistivity and cathodic protection system, as well as degradation in appearance, had been conducted twice a year, . This paper evaluated corrosion protection methods for marine structures based on the results of 12 years exposure. The results indicate that excellent systems for splash and tidal zones were polyethylene, rubber, epoxy mastic and metal wrappings. Also the cathodic protection of uncoated submerged steel pipes in noble metal wrapping at splash and tidal zones were achieved within the required current density of approximately 100mA/m2. From the field tests the corrosion resistance of organic coating was found to depend on film thickness. The laboratory tests showed that the minimum rupture energy of a sprayed urethane coating was proportional to the square of coating thickness.