In the operating state of the high-pressure swivel joint, the end face sealing portion is close to and separated from the sealing surface due to the advancement of the pressure floating seat of the supplied fluid and the advancing/retracting operation of the mandrel. That is, when the high-pressure swivel joint float is retracted and the first sealing surface and the second sealing surface are separated from each other, if the fluid is supplied to the passage hole, the fluid force acts on the side end of the fixed portion of the high pressure swivel joint The side ends are pushed up in the axial direction.
Therefore, the floating seat advances, the first sealing surface, and the second sealing surface abut, and form a close-contact end face sealing portion. Therefore, the fluid is supplied from the fixed passage to the high-pressure swivel joint rotating passage in a rotating state.
With the advancement of the high-pressure swivel joint with respect to the fixed part, the floating seat retracts and the flange portion returns to a position very close to the outer casing element.
The mandrel is retracted relative to the state by a high-pressure swivel joint, which returns to a state in which the first sealing surface and the second sealing surface are separated from each other.