| 摘要 |
PROBLEM TO BE SOLVED: To simultaneously solve such problems as high temperature strength of a temperature reserving structure of a pipe facility for high-temperature gas and corrosion of a sulfuric acid dew point by arranging bimetals warped in a direction apart from an outer wall surface, in association with temperature raising of a structure member on an inside surface of a flexible part. SOLUTION: A plurality of bimetals 7, warped in a direction apart from an outer wall surface in association with temperature raising of a valve box 2, are arranged on an inside surface of a flexible part 6. When an inside atmosphere temperature of a butterfly valve 1 is raised, a temperature of the valve box 2 is raised, and a center part of an axial core direction, that is a part corresponding to the flexible part 6 is raised. Accompanying the temperature rise of an outer wall of the valve box 2 to a prescribed temperature or higher, each bimetal 7 is warped in a direction apart from the outer wall surface, and each Tanzaku part 6a of the flexible part 6 is separated from the outer wall surface of the valve box 2. It is thus possible to hold the temperatures of structural members of the valve box 2, an outer cylinder, a pipe body, and the like at an allowable heat insulating temperature and lower and at an allowable lower limit temperature or higher, and it is also possible to simultaneously solve such antithetical problems as high-temperature strength and corrosion of a sulfuric acid dew point.
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