Safety of Tourist Submersibles (1990) / Chapter Skim
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CHAPTER 3: TECHNICAL ASPECTS OF SYSTEM DESIGN
CHAPTER 3: TECHNICAL ASPECTS OF SYSTEM DESIGN
Pages 19-30
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From page 19... ...
To date, all but two tourist submersibles have been built to ABS class, and ABS has the only set of classification rules the Coast Guard recognizes for submersible design. In addition, the American Society for Mechanical Engineers (ASME)
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From page 20... ...
ABS is currently revising its rules to add provisions for tourist submersibles. For main pressure vessel (MPV)
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From page 21... ...
To further compound the problem, HYCO Technology's ARIES, SEA VIEW, and COMEX's proposed SEABUS are proposed as cylindrical (not spherical) pressure vessels.
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From page 22... ...
operational submersibles is to reinforce cylindrical shell sections with external ring stiffeners. The rules for designing main pressure vessels using ring stiffeners are well known.
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From page 23... ...
the surveyor Could call" for critical dimensional checks. Since tourist submersibles are drydocked on land during mandated surveys every 18 months and are basically disassembled for inspection, it would be a relatively simple task to check the hull circularity and verify that it is within the allowable limits.
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From page 24... ...
Conclusions and Recommendations Regarding Design and Construction The method of tourist submersible design used within both the domestic and international industry is still maturing; hence, there are inconsistencies in industry design standards between those of the certification and classification agencies—e.g., factors of safety utilized in pressure vessel design, design parameter terminology, extent of data required during post-construction hydrostatic tests, and selection of materials used. The Coast Guard should reevaluate the areas of inconsistency with ABS (indicating a lack of adequate definition)
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From page 25... ...
The present main pressure vessel (MPV) design used for tourist submersibles in service in the United States uses a ring-stiffened cylinder where the stiffeners do not extend into the pressure vessel.
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From page 26... ...
ABS rules for submersibles require emergency breathing life support for the duration of the dive or two hours, whichever is longer. (In the case of tourist submersibles, the two-hour requirement pertains.)
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From page 27... ...
The current rebreather devices for providing emergency air supply for passengers do not satisfy ABS rules and are not adequate protection against some types of atmospheric contamination. The Coast Guard, in cooperation with ABS, should promulgate standards on emergency breathing requirements and systems for tourist submersibles.
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From page 28... ...
Years of experience with surface ships has allowed the Coast Guard to develop an inspection program under which the local inspectors are sufficiently knowledgeable to work directly between the rules and the hardware without interpretation difficulties. Inspection of tourist submersibles is not so straightforward and routine because of the relative newness of these vessels and the relative lack of experience with them on the part of Coast Guard inspectors.
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From page 29... ...
Tourist submersibles represent a new challenge for the Coast Guard inspection system. Although these vessels have much in common with surface craft, the major differences may mean that the expertise of local inspectors could be insufficient to ensure adequate periodic safety reviews.
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From page 30... ...
At, . Personnel from Coast Guard Headquarters and the Marine Safety Center should be available to provide additional in-depth fantiliari~ with tourist submersibles systems and operations.
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