included for comparison purposes. Deep ocean data from the Atlantic 

 Ocean is also included to permit comparison of the different deep 

 ocean environments, References 22 - 24, 



The corrosion rates and types of corrosion of all the metals are 

 given in Table 4. In the column designated "Crevice" an intentional 

 crevice was created on one specimen of each alloy by bolting a I-inch 

 square piece of the same alloy to the specimen with a nylon nut and 

 bolt. The corrosion rates of some of the alloys are shown graphically 

 in Figures 3 through 21, 



Water in the open sea is quite uniform in its composition through- 

 out the oceans; therefore, the corrosion rates of steels exposed 

 under similar conditions in clean sea water should be comparable. The 

 results of many investigations on the corrosion of structural steels 

 in surface sea water at many locations throughout the world show that 

 after a short period of exposure the corrosion rates are constant and 

 amount to between 3 and 5 mils per year .^■^''^' ' ° Factors which may 

 cause differences in corrosion rates outside these 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 as indicated below are compared in Figure 3: 



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



20 

 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)« 



