Characteristically, this is also the only pipe configuration tested where the 

 distribution of cracks was distinctly different from those in other pipe con- 

 figurations. In the 6x 6-inch pipe configuration, all of the cracks were radial 

 oriented along longitudinal axis of the pipe, while in other pipe configurations 

 they were mostly of the circumferential type. It would thus appear that 

 because of the low L/D ratio for the 6 x 6-inch pipe configuration, the stress 

 distribution is such that failure occurs at lower hydrostatic pressure due to 

 failure of material initiated by stress raisers on the bearing surfaces rather 

 than at the higher pressure predicted for it by elastic buckling theory. 



50,000 



10,000 



Mil 



1 — I I II I 



1-inch-ID pipe 



Tl~r 



1.5-inch-ID pipe - 



2-inch-ID pipe _ 



\ 



Legend Jv 



9 6-inch-l D pipe 



■ 4-inch-ID pipe 



A 3-inch-ID pipe 



+ 2-inch-ID pipe 



♦ 1.5-inch-ID pipe 



3- and 4-inch- 

 I D pipes 



I I I I 



6-inch-l D pipe 



J I 1 I i I 



Figu 



2 3 4 5 6 10 



Length/Diameter 



re 41. Comparison of actual pipe implosion pressures with pressures 

 calculated on the basis of Equations 2 and 3. 



In general, with only one minor exception, the plot of R. von Mises 

 equation has been found helpful in predicting the implosion pressure due to 

 buckling of glass pipes with conical flanges. Needless to say, extensive cracking 

 may, and in most cases does, occur prior to the act of implosion. Because of 

 it, the actual operational depth to which the glass housings may be repeatedly 

 subjected without damage is considerably less. The relationship between the 

 magnitude of the implosion depth and of safe operational depth can be seen 

 from comparison of Tables 2 and 6, which show the implosion pressures and 

 safe operational depths, respectively. 



44 



