Reinhart 



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. 1^ 

 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 between the 

 two locations (5.73 vs 1.4 ml/1) with the possibility that some 

 might be due to the difference in the currents (unknown in the 

 Atlantic but practically stagnant in the Pacific). The difference 

 between the corrosion rates on the surface at Harbor Island, N. C. 

 and at a depth of 5,600 feet in TOTO is attributed to differences in 

 depth (pressure, vs 2520 psi) and temperature (19°C vs 4.2°C). 



Corrosion rates for steel at a depth of about 4,500 feet ' 

 in TOTO were practically the same as those at the surface at Harbor 

 Island for comparable periods of time. 



The corrosion rates of wrought iron and Armco iron at depths 

 were comparable with those of AISI 1010 steel as shown in Figure 4. 

 The corrosion rate of wrought iron at the surface at Fort Amador in 

 the Pacific Ocean Panama Canal Zone-'-O after about 3 years of exposure 

 was approximately 7 times greater than at a depth of 5,500 feet in 

 the Pacific Ocean. 



The corrosion rates of all the alloy steels at depths of 

 5,500 and 2,350 feet in sea water are shown in Figure 5. These 

 values are shown as shaded areas encompassing most of the values. 

 The corrosion rates for these steels decreased similarly to those 

 for carbon steel with time of exposure at both depths. Although the 

 corrosion rates at a depth of 5,500 feet varied between 1.9 and 6.0 

 MPY after 123 days of exposure they were all essentially the same 

 after 1,064 days of exposure (0.5 to 0.9 MPY). The performance of 

 these same steels when partially embedded in the bottom sediments 

 is shown in Figure 6. After 1,064 days of exposure at a depth of 

 5,500 feet, the corrosion rates were the same as those in the sea 

 water above the bottom sediments. However, the corrosion rates for 

 many of the steels after 403 days of exposure in the bottom sediments 

 at a depth of 6,780 feet were less than 0.5 MPY; this is attributed 

 to the greater proportion of each specimen that was embedded in the 

 bottom sediment. The specimens of these particular steels were about 

 2 inch diameter discs and in all probability were nearly completely 

 embedded in the bottom sediment. 



The data for all the steels was analyzed statistically. The 

 mean curve of the corrosion rates and 95 percent confidence limits 

 are shown in Figure 7 for the specimens exposed in the sea water. 

 The corrosion rate curves for AISI 1010 steel and high-strength-low 

 alloy steel #2 exposed at a depth of 5,600 feet in TOTO are also 

 included to reveal that they are outside the 95 percent confidence 

 limits. The fact that they are outside the 95 percent confidence 

 limits of the corrosion rates of the steels exposed at a depth of 

 5,500 feet in the Pacific Ocean indicates that the environment in 

 the Atlantic Ocean is somewhat different from the environment in the 

 Pacific Ocean. The median curve of corrosion rates for the 2,350 

 foot depth is below that for the 5,500 foot depth indicating a 

 difference in environment even though the confidence limits overlap. 



268 



