Reinhart 



limits are variations in marine fouling, contamination of the sea 

 water near the shorelines, variations in sea water velocity, and 

 differences in the surface water temperature. 



IRONS AND STEELS 



Corrosion 



The corrosion rates of low carbon steels in sea water at 

 different locations are compared in Figure 3: 



a. Surface waters of the Atlantic Ocean at Harbor Island, 

 North Carolina; 



b. Surface waters of the Pacific Ocean at Fort Amador, 

 Panama Canal Zone; 



c. Deep Atlantic Ocean waters, Tongue- of -the-Ocean, 

 Bahamas; ''°»" 



d. Deep Pacific Ocean waters, Port Hueneme, California. 



The corrosion rates of the steels at the surface in both the 

 Atlantic and Pacific Oceans decrease rather rapidly with time and 

 become relatively constant after about 2 to 3 years of uninterrupted 

 exposure. The higher corrosion rates at Fort Amador are attributed 

 to the difference in temperature between the two sites (27°C vs 21°C). 



The corrosion rates of the steels exposed at nominal depths 

 of 5,500 and 2,350 feet in the Pacific Ocean also decreased with 

 time of exposure and were consistently lower than the surface 

 corrosion rates. These lower corrosion rates are attributed to the 

 combined effects of the differences between the variables at the 

 surface and at the two depths; temperature, pressure and oxygen con- 

 centration. 



Also, the corrosion rates at a depth of 2,350 feet were 

 lower than those at a depth of 5,500 feet. In this case the lower 

 corrosion rates at a depth of 2,350 are attributed to the combined 

 effects of the differences between the variables at the two depths; 

 temperature, pressure and oxygen concentration. 



The above differences in the corrosion rates cannot be 

 attributed chiefly to any one variable because of the interdependence 

 of one variable on another. For example, the solubility of oxygen 

 in sea water is increased as the pressure is increased at constant 

 temperature but at constant pressure the solubility of oxygen de- 

 creases as the temperature increases. 



The corrosion rates at a depth of 5,500 feet in the Pacific 

 Ocean were about one-third the rate of the steels at Harbor Island 

 after about 3 years of exposure. 



The corrosion rates for a steel exposed by the Naval 

 Research Laboratory at a depth of 5,600 feet in the Tongue-of -the- 

 Ocean in the Atlantic were slightly higher than those in this 



267 



