The reliability of marine fittings is discussed. All fittings, whether electric, hydraulic or pneumatic, can be put into one of three classes: A) those of continuous action; B) those of periodic action; C) those of single action. Class A includes valves which operate continuously and are only rarely closed for inspections or other purposes. Class B includes similar valves which are periodically open and closed as required by the changing parameters which they control. Group C includes fire whistles, Kingston valves, and other fittings which must be always ready to trigger but which operate intermittently. The concepts of reliability include failure-free operation, efficiency, lifetime, maintenance, and breakdown effect, with reliability being determined by the weakest element. The main failures of classes A and B are leakage of the seals, packing, etc, which can be corrected by routine maintenance. Class C failures result from aging processes, such as corrosion. Stand tests are not considered satisfactory for reliability studies, because they fail to duplicate actual working conditions. It is noted that, quite frequently, the number of fittings in service is insufficient for statistical analysis. Electronic reliability theory can not be adopted because it fails to account for the interdependence of the elements and processes. The authors believe that a new reliability theory should be developed--one which would combine test results with operational data. Meanwhile, the weakest elements should be improved.

  • Authors:
    • Manerov, V V
    • Pyasik, I B
  • Publication Date: 1968

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Filing Info

  • Accession Number: 00014957
  • Record Type: Publication
  • Source Agency: Joint Publications Research Service
  • Files: TRIS
  • Created Date: May 7 1973 12:00AM