VALVE DEVICE FOR DOUBLE STRUCTURE PIPELINE

PROBLEM TO BE SOLVED: To provide a valve device for controlling a fluid flowing in an inner passage of a double structure pipeline, in such a way as to be able to secure smooth fluid flow and easy to handle. SOLUTION: An inner valve casing 2 communicated with an inner pipe of a double structure pipeline so as to form an inner passage, and an outer valve casing 3 fitted with play to the outside of the inner valve casing 2 so that an outer passage formed between the outer valve casing 3 and the outer peripheral surface of the inner valve casing 2 is communicated with an outer pipe, are provided concentrically. An inner passage valve stem 6 radially piercing the inner valve casing 2 is provided rotatably around an axis being supported to the outer valve casing 3, and a valve element 7 rotated between a closing position of closing the inner passage and an opening position of opening the inner passage is disposed in the inner valve casing 2 and fixedly connected to the inner passage valve stem 6. A valve device is thereby maintained in double structure formed of the inner valve casing 2 and the outer valve casing 3, and a passage cross section becomes constant while being simplified in outer shape.