Conclusion 



To forestall this type of failure, information must be made available 

 to the vessel designers, and safe vessel operation techniques must be taught to 

 the pressure vessel operators. Such information to be of real value as a design 

 guide must constitute a theoretically postulated and experimentally verified 

 series of equations. 



Recommendation 



In order to obtain the needed information to design vessels resistant 

 to implosion damage, and to insure the safe operation of vessels already in 

 existence, a program must be initiated to investigate the effect of implosions 

 on pressure vessel life. Such a program should consist of experimental and 

 analytical studies running concurrently. Only from the continual cross-referencing 

 of experimental and analytical work will biable design criteria emerge from 

 such a program. 



SELECTION OF SAFETY FACTOR 



The safety factor for pressure-vessel operation generally is based on 

 four considerations. These are: 



1. Foreseeable inaccuracies in the stress analysis during design on the vessel 



2. Predictable discrepancies between the properties of the material samples, 

 and the actual properties of the material in the vessel 



3. Unforeseen loads that will act on the vessel while under maximum working 

 pressure 



4. Number of pressure cycles to which vessel will be subjected during its life 



In the proposed pressure test facility, only items 2, 3, and 4 are decisive, 

 if a vessel construction concept with known design criteria is chosen. The 

 discrepancy between the properties of the specified material and those actually 

 found in the vessel structure will be very large since the construction of the 

 proposed vessel requires that very thick forgings be employed for the closures 

 and flanges. The actual magnitude of discrepancy is not known since very little 

 is known about this subject for very heavy forgings. The same may be said of 

 our knowledge in the generation of shock loads in pressure vessels by implosion 

 of test models. That large shock waves are triggered by implosion is well known. 



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