To reduce manufacturing cost and to improve workability by positively supporting a support bracket with extremely simple structure with the small number of part items, and positively preventing the fall of a clamping bolt from the support bracket.

A duct 21 is fitted to a nozzle of a piping equipment 20. A metal belt of a clamping device 22 is fitted to the fitting part, and a clamping bolt 27 of the clamping device 22 is rotated being supported by a support bracket 25 protrusively provided at the piping equipment 20. A bolt support hole 31 for rotatably supporting the clamping bolt 27, a large-diameter bolt insert hole 32 allowing the insertion of a head 28 of the clamping bolt 27, and a communicating part 33 for connecting both holes are formed at the support bracket 25. The clamping bolt 21 is inserted in the bolt insert hole 32 of the support bracket 25 from the head part 28 and radially displaced from that state to be engaged into the bolt support hole 31 via the communicating part 33.