Manhole structures, multi-shell tanks and ships

The manhole structure with a fused joint and optional backing rings enhances airtightness, addressing gas leakage issues in tanks storing liquefied gases, ensuring effective sealing and vacuum maintenance.

JP7828445B2Active Publication Date: 2026-03-11KAWASAKI JUKOGYO KK
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
Filing Date
2023-05-25
Publication Date
2026-03-11

AI Technical Summary

Technical Problem

Existing manhole structures in tanks storing liquefied gases face challenges in maintaining airtightness, leading to potential gas leakage or ingress through gaps between the manhole cover and body, especially when dealing with small molecular gases like hydrogen or helium.

Method used

A manhole structure featuring a cylindrical manhole body and cover joined by a fused joint, such as welding, to enhance airtightness, with optional backing rings and annular plates for stable welding and spark containment.

Benefits of technology

The fused joint manhole structure provides higher airtightness, preventing gas leakage and maintaining vacuum levels within the tank, suitable for multi-shell tanks and ships carrying liquefied gases.

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Patent Text Reader

Abstract

A manhole structure disposed on a wall of a tank that contains a liquefied gas, the manhole structure comprising: a tubular manhole body which is bonded to the wall on which the manhole structure is disposed, and protrudes inward or outward from the wall; a manhole lid that closes a manhole formed by the manhole body; and a melt-bonding portion bonding the manhole body and the manhole lid.
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Citation Information

Patent Citations

  • Method of joinning steel pipes

    JP1976128653A

  • container lid or flange lid

    JP2005537995A

  • Manhole structure of tank

    JP2011084316A

  • Double-shell tank

    JP2020015535A

  • Transport container for liquefied gas

    WO2014097974A1