Unclassified 



DOCUMENT CONTROL DATA R&D 



Naval Civil Engineering Laboratory 

 Port Hueneme, Calif. 93041 



Unclassified 



RELATIONSHIP BETWEEN MARINE FOULING AND CORROSION RATE OF CARBON 

 STEEL AND ALUMINUM ALLOY AT THE SURFACE AND AT 6,000-FOOT DEPTH 



iiPTivE NOTES (Type o/ report and Inclusive da 



Not final; June 1967-June 1969 



liddle Inlllal, Im 



J. S. Muraoka 



May 1970 



53 



19 



6. PBo.ECTNo YF 51.543.007.01.001 



TR-681 



This docunnent has been approved for public release and sale; its distribution is unlimited. 



Naval Facilities Engineering Comnnand 

 Washington, D. C. 20390 



Carbon steel (1010) and aluminum alloy (7178-T6) panels were exposed at the surface 

 (23 to 286 days) and at 6,000-foot depth (189 days) in the Pacific Ocean (1) to determine 

 the effects of fouling organisms on the corrosion rate and (2) to compare the biological 

 corrosion rate of identical test panels submerged at the two depths. Seawater samples 

 obtained at the surface and at depth were analyzed for dissolved oxygen concentration, pH, 

 salinity and temperature. Bacteriological tests were also conducted on seawater samples. 

 The test panels were submerged in the sea as follows to obtain data on corrosion rates: 

 (1 ) enclosed inside an initially sterile plastic cylindrical chamber with both ends sealed with 

 membrane filters (control panels), (2) placed inside a cylinder covered with 210-mesh nylon 

 screen cloth, (3) placed inside a cylinder with both ends uncovered, and (4) attached to a 

 phenolic plastic strip (exposed panels). The control specimens became contaminated; however, 

 from corrosion data obtained on test panels exposed on the seafloor in 6,000 feet of water, 

 it is concluded that slime films played a significant role in accelerating corrosion of test 

 specimens. Test panels exposed at the surface corroded at faster rates than replicate test 

 panels which were exposed on the seafloor in 6,000 feet of water. The corrosion rates of 

 both steel and aluminum alloy panels approach constancy after extended exposure in the sea. 

 The various environmental factors and their effects on the corrosion rates at the surface of 

 the sea and at great depth on the seafloor are discussed. 



DD 



„1473 



S/N 0101-607.680 1 



Unclassified 



Secuntv Classify 



