wire windings. Thus, under operating conditions the inner core may be 

 considered to have both internal and external pressures acting upon it and 

 the windings to have induced stresses resulting from the winding tension and 

 the internal pressure. 



Acceptable design procedures are available for wire-wound cylindrical 

 shells, which are based on the allowable stress in the inner core. Further 

 investigation is required to determine the benefits of applying the windings 

 at a variable tension to produce a constant tension under operating conditions. 



It has not been possible to obtain any information on companies 

 which currently undertake wire winding of cylinders of the size contemplated. 

 It is not likely that such companies exist within the United States. It is felt 

 that should this concept be accepted, a considerable amount of time, and 

 therefore expense, will be involved in setting up a facility whereby the fabri- 

 cation could be accomplished, particularly for the preferable on-site fabrication. 



Desirable Features 



1. Imposition of prestress on the inner vessel shell by tensioned wires makes 

 thinner vessel walls feasible than in stacked-ring or monobloc vessels. 



2. Wire utilizes steel with strength in excess of 250,000 psi that is not available 

 for multilayer or monobloc vessels. This permits further reduction in vessel 

 thickness as compared to multilayer vessels. 



3. Fracture crack propagation will be arrested at the inner vessel— wire layer 

 interface. 



Undesirable Features 



1. Retaining the wire windings at each end of the vessel may be difficult. 



2. Yielding the wire in one or more places during winding could occur without 

 the fabricator's knowledge. 



3. Abrasion and friction would occur between the wires in loading and unload- 

 ing cycles. 



4. Redistribution of tensions within the winding due to creep may occur. 



5. Early fatigue failure of wires in cyclic loading may result from stress raisers 

 in the form of localized abrasion and corrosion. 



6. The expense involved in setting up an on-site winding facility will far exceed 

 the transportation costs of a large vessel based on alternative concepts. 



