SECTION 1 

 INTRODUCTION 



Between 1962 and 1970 the Civil Engineering 

 Laboratory, Naval Construction Battalion Center, 

 Port Hueneme, California, exposed approximately 

 20,000 specimens of about 475 different alloys in the 

 Pacific Ocean. These specimens were exposed at the 

 surface and at nominal depths of 2,500 and 6,000 

 feet for periods of time varying from 123 to 1,064 

 days. 



The purpose of these exposures was to provide 

 the Naval Facilities Engineering Command 

 (NAVFAC) with information on the deterioration of 

 materials in deep-ocean environments. Such informa- 

 tion was needed to improve techniques, to develop 

 new techniques pertaining to naval material, and to 

 support the increasing interest in the deep ocean as an 

 operating environment. 



The Naval Facilities Engineering Command is 

 charged with the responsibility for the construction 

 and maintenance of all fixed Naval facilities; hence, 

 the construction and maintenance of Naval structures 

 at depths in the oceans are but one facet of its overall 

 responsibility. Fundamental to the design, construc- 

 tion, maintenance, and operation of structures and 

 their related facilities is information on the deteriora- 

 tion of materials in a particular environment. Since 

 there was very little published information on the 

 behavior of construction materials in deep-ocean 

 environments, this program was initiated in 1960 to 

 obtain such information. 



In-situ testing was chosen because it is not 

 possible to duplicate all the variables and the changes 

 in these variables that prevail in any one environment 

 or location. A test site was considered suitable if the 

 circulation (currents), sedimentation, and bottom 

 conditions were representative of open ocean condi- 

 tions: (1) the bottom should be reasonably flat, (2) 

 the site should be open and not located in an area of 

 restricted circulation, such as a silled basin, (3) the 

 site should be reasonably close to Port Hueneme for 

 ship operations, and (4) the site should be within the 

 operating range of the more precise navigating and 

 locating techniques. 



A Pacific Ocean site meeting these requirements 

 was selected at a nominal depth of 6,000 feet. The 

 ocean bottom at this site is relatively flat in a broad 

 submarine valley southwest of San Miguel Island, 

 California; it is readily accessible to the Civil Engi- 

 neering Laboratory; and it is subject to the effects of 

 ocean currents. This site, designated Test Site I, is 

 approximately 81 nautical miles southwest of Port 

 Hueneme, latitude 33°44'N, longitude 120°45'W. 



Oceanographic data collected between 1961 and 

 1963 [1,2] show the presence of an oxygen mini- 

 mum zone at depths between 2,000 and 3,000 feet. 

 This minimum oxygen zone was present at all sites 

 investigated when the ocean floor was at depths 

 varying between 2,000 and 13,000 feet. 



It is well known that the corrosion rates of many 

 materials (e.g., steels) are affected by the concen- 

 tration of oxygen in the environment. Because of 

 this, it was decided to establish a second test site, 

 Test Site II, in this minimum oxygen concentration 

 zone where, it was thought, much pertinent informa- 

 tion could be obtained. Test Site II (nominal depth of 

 2,500 feet) is 75 nautical miles west of Port Hue- 

 neme, latitude 34°06'N, longitude 120°42'W. 



The oceanographic investigations by the Civil 

 Engineering Laboratory also disclosed that the ocean 

 floor at these sites is rather firm and was charac- 

 terized as sandy, green cohesive mud (partially 

 glauconite) with some rocks. Biological cultures of 

 these bottom sediments showed the presence of 

 sulfate-reducing bacteria in at least the first 6 inches 

 of sediment. 



In order to determine the differences between the 

 corrosiveness of seawater at depths and at the surface 

 in the Pacific Ocean, it is desirable to compare 

 deep-ocean corrosion data with surface immersion 

 data. Since surface data from the Pacific Ocean in the 

 vicinity of Port Hueneme were not available in the 

 literature for most of the alloys exposed at depths in 

 the Pacific Ocean, it was decided to establish a sur- 

 face exposure site to obtain this information. There- 

 fore, a third site, Test Site V, was established at the 



