20,000 



1 2,000 



94-8 specimen 



imploded at 



18,000 psi 



Vi 



( / 



/ 



/// 



M 



J 



- cm 



/// 



—da- 

 III 



A- 



Qi-D 



// 



r 



/ 



Note: 

 Internal volume 

 1,200 ml at 

 atmospheric pressure 



I I 



Legend 



n 94-7 specimen 

 A 94-8 specimen 



O 107-2 specimen 



I I 



The 6061-T6 aluminum and the 

 phenolic resin— impregnated glass fiber 

 laminate materials performed the best 

 under a single pressurization to implo- 

 sion. However, the cost of both the 

 basic material and the machining of tlie 

 glass laminate end closures is much 

 greater than that of the aluminum end 

 closures. For this reason the 6061 -T6 

 aluminum is considered the best choice 

 based on these tests. 



The second series of five speci- 

 mens of each glass pipe— end closure 

 combination was tested for cyclical 

 performance. Cyclical tests started 

 with 10 cycles from psi to 5,000 psi. 

 Specimen assemblies were then dis- 

 assembled and examined, and the 

 next cycling pressure was selected on 

 the basis of the just completed test. 

 Subsequent cycling tests at successively 

 lower pressures were conducted as 

 indicated in Table 4. The pressuriza- 

 tion rate was held at 1,000 psi per 

 minute in all tests. 



Based on these tests, naval 

 brass appears to be the best choice 

 for limited cycling service under this 

 set of conditions. 



A third series of experiments was designed to evaluate the effectiveness 

 of various "gasket" (sealing and bearing) systems designed to interpose a "soft" 

 bearing and sealing element between the end of the glass pipe and the type 316 

 stainless steel end-closure plate selected for these tests; effectiveness was gaged 

 by the increase in the cyclical depth range of the glass pipe under test. 



The gasket systems were designed to serve three functions. ( 1 ) to 

 provide a watertight seal between the glass pipe and end-closure disc at both 

 low and high pressures; (2) to eliminate stress concentrations due to point 

 contact between the somewhat uneven glass bearing surface and the steel 

 end-closure material; (3) to provide a "mobile" surface on which the glass 

 pipe end flange could move as the pipe diameter decreased in response to 

 external pressure. 



10 20 30 40 50 



Accumulated Volume Change (ml) 



Figure 15. Graphic plot of the volume of 

 water displaced from three 

 water-filled, 4-inch-ID x 6-inch- 

 long glass pipe assemblies 

 subjected to incrpasing hydro- 

 static pressure. 



17 



