RELIABILITZ/SAFETY ' ' 



The present IIY-IJO pressure capsule for ALVIM has a predicted 

 collapse depth of apprcidrnately 16,000 ft. The ]"i'-100 steel pressure 

 hull material has been vidoly used in mari.ne slri:otu.r'es (ii;cluding 

 structural -Ticdels yith rield strengths in excess of 90,000 psi) aiid 

 can bo considered as a reliable veil documantcd material. Thus for 

 a given collapse depth, a deeper operating dpethjcan be justified for 

 the irif-100 sphere, Corz/ersely a minimum of ifxijeri mental data exists 

 on the collapse strerigth of spherical titaniujri hulls. Thus prudence 

 would require a more conservative approach in establishing an operating 

 depth (based on colla].i£<5 tests) for the titanium. The existing certifi- 

 cation specifications require a minimiun factor of 1.5 on colla])se over 

 operating depth - t?rjs for the titaniuin sphere a factor soxevhat greater 

 than 1.5 seems desirable at this time. In this regard a goal of 1?,000 

 ft as the collapse depih is feasible and should as a minin-jm permit 

 operations to a depth cf 9,000 ft. I-Jhen more extensive operational and 

 test data are generated and the degree of confidence in the titaniiam is 

 increased, an increase of the operating depth can be considered. 



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