being subjected to high compressive stresses. Much work is required to 

 evaluate this, and other, improved designs for adhesive joints. It is 

 important that the presence of the groove for the adhesive joint did not 

 seem to impair the collapse strength of the models. 



In addition to deterioration due to loading, adhesive materials are 

 subject to eventual deterioration due to exposure to salt water and to 

 biological fouling. These material problems must be solved by developing 

 new adhesives and material -protection techniques. Until they are solved, 

 adhesives will be limited to short-term applications or will require 

 periodic replacement. 



The primary advantage of ring construction is that it permits the 

 use of many light, high-strength nonweldable materials for deep-submergence 

 pressure hulls; but there are a number of other features which may 

 produce considerable savings . The combining of rings into a pressure hull 

 by mechanical means is essentially a faster and less expensive operation 

 than welding and requires less time spent in the shipway. This potential 

 saving is balanced by the greater machining costs associated with ring 

 construction. In addition, it is often necessary to open a hull to make 

 repairs or to replace machinery. It is not possible to open a hull by 

 cutting or burning a ring since it cannot ordinarily be rewelded; but it 

 may be practical to separate two rings at a joint, and then reassemble the 

 section after the repair work is completed. 



Present forging capacity limits the maximum size of nonweldable 

 metals to a diameter of about 12 to 15 feet. Aluminum must be forged to 

 obtain its highest yield strength, but titanium and steel may be welded and 

 then heat treated to higher strengths. It is felt that the primary 

 applications of ring construction will be in structures of smaller 

 diameter. The possibilities of ring construction in onsite assembly of 

 undersea laboratories and in oceanographic research vehicles have already 

 been mentioned. In addition, the technique can find military applications 

 for deep-running-torpedo housings or for submerged missile-silos. 



