sea water, when no fouling organisms become attached to small, fully 

 immersed specimens, corrosion of steel at 11.1°C proceeded at 7 MPY 

 compared with 14 MPY at 21.1°C, This increase (tvzofold) corresponds 

 with what would be expected from chemical kinetics, where the rate 

 of reaction is approximately doubled for a rise of 10°C. 



Uhlig^ has shown that the corrosion rate of iron in air saturat- 

 ed water is proportional to the oxygen concentration. Re has also 

 conducted experiments in the laboratory which show that at constant 

 temperature the corrosion rate of steel in a calcium chloride solution 

 increases in direct proportion to increase in oxygen concentration. 



When steel is in free contact with sea water its corrosion rate 

 increases as the velocity of the water increases „' 



Within the range of about pH 4 to 10, the corrosion rate of 

 steel in aerated water at room temperature is independent of pH, 

 and depends only on how rapidly oxygen diffuses to the metal surface. 



L, L, Schreir states; "It is a remarkable and important fact 

 that except where there is gross dilution or contamination, the 

 relative proportions of the major constituents of sea water are 

 practically constant all over the world," "In the major oceans the 

 salinity of sea water does not vary widely, lying in general between 

 33 and 37 parts per thousand; 35 parts per thousand is coimiionly 

 taken as the average for "open- sea" water." Nevertheless, the corro- 

 sion rates at a depth of 5,500 feet in the Pacific Ocean were about 

 one-third the rate of the steels at Rarbor Island after about 3 

 years of exposure. 



Variables which were different between the surface in the 

 Atlantic Ocean at Harbor Island, North Carolina, and at a depth of 

 5,500 feet in the Pacific Ocean are given in Table 5, The current 

 at the surface was variable in direction and magnitude, being due 

 only to normal tidal action; at depth in the Pacific Ocean there was 

 practically no current; hence, there was probably very little effect 

 due to differences in current alone. As discussed above, the dif- 

 ference in pR between the two sites would be expected to be ineffectual, 

 Hence, the difference in corrosion rates is attributed to differences 

 in pressure, temperature and oxygen concentration. 



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 investigation, 

 Figure 3, Oceanographic data reported for the Tongue-of-the-Ocean 

 are; depth, 4,967 feet; 4,18°C and 5.73 ml/1 oxygen.^^ Since the 

 differences between the depths, pressures and temperatures are small 

 the higher corrosion rates in the Atlantic are attributed chiefly 

 to the difference in the concentration of oxygen betxireen the two 



