Patent ID: 8096590
Filing Date: 2012-01-17
Classification: F16L

Abstract:
1. A connecting structure for piping comprising a first piping provided, at an end portion of a piping main body, with a bead portion expanding toward an outer side of a radial direction, the first piping being connected to a second piping, wherein a piping side tube portion, having a larger outer diameter than a piping main body that forms the second piping, is provided at an end of the piping main body that forms the second piping; a piping side stopper is provided in the piping side tube portion and a male screw is provided on a peripheral portion of the piping side tube portion; a bead portion insertion hole, into which the bead portion is insertable on the same axis as the piping side tube portion, is provided on an inner circumference of the piping side tube portion close to the piping main body; a seal material insertion hole having a larger diameter than the bead portion insertion hole that is open to the end of the piping side tube portion is provided on the same axis as the bead portion insertion hole on an inner circumference of the piping side tube portion close to the end; and an annular seal material pressure-contact surface, facing a direction of the end, is provided at a location that is a boundary between the bead portion insertion hole and the seal material insertion hole; a nut member is provided including a large diameter tube portion having a female screw, threadable onto the male screw, formed on an inner circumferential surface; a small diameter tube portion having an inner circumferential surface through which the bead portion is insertable, and that is inserted into the seal material insertion hole by the female screw being threaded onto the male screw; and a nut side stopper that is abuttable to the piping side stopper; the end portion having the bead portion of the piping main body of the first piping is inserted into the bead portion insertion hole; a seal material and a washer, which are fitted to a location of the piping main body located opposite the end of the piping main body of the first piping across from the bead portion, are inserted into the seal material insertion hole; and, in this state, the nut member is joined with the piping side tube portion by the female screw being threaded onto the male screw until the piping side stopper and the nut side stopper are abutted; wherein in the state where the piping side stopper and the nut side stopper are abutted, the seal material is compressed in an axial direction via the washer by the small diameter tube portion and the seal material pressure-contact surface; and the seal material is elastically joined to the outer circumferential surface of the piping main body of the first piping and the inner circumferential surface of the bead portion insertion hole in the radial direction; and further comprising a plurality of through holes in the piping side tube portion and in the nut member; and a rotation prevention member at an end close to the piping main body of the piping side tube portion; wherein the plurality of through holes enable insertion of the rotation prevention member and are arranged at intervals in a circumferential direction throughout a location close to an end wall portion of the large diameter tube portion and throughout the end wall portion.