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DEVELOPING BLANKING DEVICE FOR HULL OPENINGS FOR USE DURING THE UNDERWATER INSPECTION OF VLCC AND ULCC VESSELS

Under provisional Rules issued by NK, ABS, and LR, surveys of large ships in dry dock (except special periodical surveys) can be replaced by underwater inspections. In such inspections, closing of the sea-water suction and discharge openings presents a problem, and the Authors report on a diaphragm-type blanking device, made of synthetic rubber, which has been developed (in a suction and a discharge version) for its solution. Shop tests showed that the device meets the Rules requiring that the sea connection be completely closed from outside while a sea valve is being overhauled in the ship. It was found that, to prevent leakage the air pressure on the diaphragm should be at least 0.8 kg/cm square above the hydrostatic pressure of the water. One closing device for discharge can be used for sea connections of the water. One closing device for discharge can be used for sea connections of four different sizes; for large connections, as the external force becomes greater either air-pressure or diaphragm breadth must be increased; provision of supporting pieces to supplement the air pressure is recommended. To decrease the weight for ease of handling, grp is recommended as a construction material.

  • Corporate Authors:

    Hitachi Zonsen Company Limited, Technical Inst

    60, Sakurajima Kitanomachi, Konohanaku
    Osaka,   Japan 
  • Authors:
    • Hamano, S
    • Tsuna, H
  • Publication Date: 1977-3

Language

  • Japanese

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00173037
  • Record Type: Publication
  • Source Agency: British Ship Research Association
  • Files: TRIS
  • Created Date: Apr 12 1978 12:00AM