JOINT STRUCTURE FOR VACUUM-HEAT-INSULATED DOUBLE TUBE FOR LOW TEMPERATURE FLUID

摘要

A joint structure for a vacuum-heat-insulated double tube for a low-temperature fluid has inner tubes and outer tubes fitted over the inner tubes with a vacuum layer provided between each of the inner tubes and a corresponding outer tube. The connection end-side portion of each of a pair of such vacuum-heat-insulated double tubes, the portion having a predetermined length, comprises an inner tube expanded-diameter section formed by expanding the diameter of the inner tube in a stepped shape with an annular wall section provided between the inner tube and the inner tube expanded-diameter section. An inner tube member for a joint, the inner tube member having a vacuum-heat-insulated double tube structure and having the same inner diameter as the inner tube, is provided on the inner peripheral side of the pair of inner tube expanded-diameter sections. The inner tube member for a joint is disposed without contact with the pair of inner tube expanded-diameter sections and without contact with the inner tubes. A pair of joint flanges provided at ends of the pair of vacuum-heat-insulated double tubes are fastened by a plurality of bolts and nuts.