Figure 9. Appearance of glass-to-metal contact area and RTV silicone rubber 

 seal before the tie bolts were torqued. 



Based on this information it was concluded that the practice of 

 partially filling the specimens with water did not affect the test results as 

 long as a minimum of 10% to 15% of the total internal volume of the test 

 glass specimen was filled with air at atmospheric pressure when the speci- 

 men was assembled. 



The test results, presented in Table 2, indicate that "off-the-shelf" 

 glass pipe of the type tested will provide reliable, transparent, nonmagnetic 

 instrument or light housings for a single submersion to any depth to be 

 found in the ocean, provided the appropriate diameter and length are 

 chosen. Relatively large housings (6-inch-ID x 18 inches long) are useful 

 for at least one cycle to depths of 5,000 feet with a safety factor of 2 

 when used in a system with simple 6060-T6 aluminum end plates. 



Phase II: Gasket System Tests 



The second phase of the study consisted of testing a number of 

 different glass pipe-to-end closure bearing and sealing systems. The objective 

 was to develop an end-closure system capable of withstanding the maximum 

 critical pressure and satisfactory for repeated exposure to external hydro- 

 static pressure (pressure cycling service). 



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