to gird the whole vessel with a yoke restraint of laminar construction. The 

 end-closure flanges could be modularized by assemblmg them from segments 

 similar to those found in the cylindrical section of the vessel. 



The end closure also could be assembled from some smaller modules 

 as it was already proposed for the end closure on the stacked-ring pressure 

 vessel. 



The assembly of end closures from modules makes the modularization 

 of a pressure vessel complete, since the external tie rods that hold the end 

 flanges together can be considered modules. If the vessel is completely modu- 

 larized, the internal diameter of the vessel can be increased by a factor of 2 

 to 5 over that of a stacked-ring pressure vessel, and 5 to 1 times over a mono- 

 lithic pressure vessel of 13,500-psi pressure capability. It would thus appear 

 that if the pressure vessel designs are ranked according to their adaptability 

 for constructing pressure vessels over 10 feet in diameter, the segmented design 

 with modularized retaining flanges and end closures (or laminated yoke and 

 bearing blocks) is the more adaptable. When ranked in terms of overall weight 

 and cost for a vessel diameter size that can be built either by the segmented 

 or stacked-ring method, the stacked-ring structure weighs and costs consider- 

 ably less. The real advantage of the segmented vessel design lies simply in the 

 fact that by using that particular design approach, pressure vessels of much 

 larger diameter can be built for the same pressure than by using the stacked- 

 ring design. 



EXPERIMENTAL STUDY DESIGN 



General 



Since the experimental study on the evaluation of stacked-ring and 

 segmented-wall pressure vessel designs was only exploratory, most of the 

 effort was devoted to evaluating a selected vessel design rather than studying 

 structural parameters that control the structural integrity of such vessels. In 

 other words, the approach was to ( 1 ) design and fabricate a stacked-ring and 

 a segmented-wall pressure vessel of comparable size without taking the stress 

 raisers into consideration and (2) pressurize the vessels to failure to determine 

 deviation from the predicted failure pressure, which was selected to be the 

 same for both. The difference between the predicted and experimental perfor- 

 mance of the vessels would serve as a good indicator of the magnitude of stress 

 raisers in the structure, while the comparison of experimental failure pressures 

 from the stacked-ring and segmented-wall vessels would show which is more 

 economical on the basis of psi/lb of structure weight. Also, if time permitted, 

 some exploratory investigations could be undertaken into structural details 

 that could have contributed to the early failure of the model vessels. 



17 



