To automate switching operation of a swing bend for switching combination of connection of a plurality of fixed pipes to improve the workability.

An expansion joint 6 connected with the fixed pipe 1 and a rotatable pipe 9 are mutually connected by pneumatic cylinders 14a to 14c. The rotatable pipe 9 is rotated and driven by a motor 13, and one end 17a of the U-shaped bend 17 is fixed to the other end of the rotatable pipe 9. Forward and backward movable pipes 10 to 12 are fixed to the fixed pipes 2 to 4 connected selectively with the fixed pipe 1 through an expansion joint 7. The forward and backward movable pipes 10 to 12 and the other end 17b of the U-shaped bend 17 are mutually connected by pneumatic cylinders 18a to 18c. When connection is switched, a connection part is opened, and the U-shaped bend 17 is rotated and driven to a new connection position.