Figure 27. Failed segmented end-closure retaining ring. 



DISCUSSION OF FINDINGS 



Although the structural components of the acrylic stacked-ring and 

 segmented-wall pressure vessels failed at different pressures, and in many cases 

 below their expected load-carrying capacity, several generalizations can be 

 made about the behavior of these two different vessel designs. 



First, it appears that the stacked-ring modules are the only structural 

 components in the two vessel designs that; ( 1 ) possess no stress raisers, 

 (2) can be stress-analyzed reliably, (3) have a failure stress level independent 

 of their fit with other structural components, or machining tolerances, and 

 (4) have the optimized shape for carrying the loading imposed on them. 

 Therefore, they should be utilized in the construction of ocean-environment 

 simulators as large in diameter and high in pressure capability as the fabrication 

 capability of the steel industry permits. In cases where the material properties 

 of thick high-strength forgings are well known, forgings are to be preferred 

 over laminated rings, as both the stress analysis and quality control are well 

 understood. Where a sufficiently thick ring forging cannot be made, or the 

 properties of thick forgings are uncertain, welded concentric laminations can 

 be used for individual stacked-ring fabrication. 



33 



