PURPOSE: To avoid disengagement of piping and to cope with frequent change of types of the piping by attaching each end of the pipes to be connected, to each flange, by letting the flanges act so as to freely come into contact with and part from each other, by providing valve seat at each pipe end, by providing a valve body in each valve seat, and by providing a means for tightening the flanges.

CONSTITUTION: A fluid supply pipe 2 of a movable equipment A is attached to an upper flange 1. A valve body 6 goes near and away with respect to a valve seat 5 in a pipe end part 4 by means of a cylinder 8. A pipe end part 20 of a fixed equipment B is attached to a lower flange 15. A valve body 24 is provided in the pipe end part 20 so as to be freely come into contact with and parted from a valve seat by means of a cylinder 22. When the lower flange 15 is lifted up and comes in contact with the flange 1 closely, the valve seat 5 comes in contact with the valve seat 21 closely. If the valve bodies 6 and 24 engaged with the valve seats 5 and 21 are operated separately by means of the cylinders 8 and 22, the fluid inside the a movable equipment A is supplied into the fixed equipment B. As a result, leakage of the liquid from the pipe end part does not occur absolutely.