6 inches long. I nterposed between the glass elements are two aluminum rings 

 provided with fiber-reinforced neoprene washers, which provide a compliant 

 seat between the glass and metal components. Sealing was effected by the 

 use of a silicone grease, and initial compression was supplied by tensioned 

 tie rods and metallic pipe flanges. 



This assembly was pressure tested and found to fail at an average of 

 2,800 psi. Subsequent pressure cycling at 1,000 psi demonstrated the use- 

 fulness and reliability of this system at depths to approximately 2,000 feet 

 in cyclical service. 



MODES OF FAILURE 



The specimens failed in two ways: cracking followed by implosion 

 and cracking without implosion. Those which cracked without implosion 

 probably would have imploded had pressurization been continued beyond 

 the 20,000-psi limit used in these tests. 



Figure 33. Prototype deep-submergence light for 10,000-foot depth service 

 using 1-1/2-lnch-ID x 6-inch-long glass pipe. 



31 



