Joint pipe

A pipe joint, comprising:

• a flare joint body (1F) including a male screw part (9) and a slope surface (5) with reduced-diameter tip;
• a cap nut (2) including a female screw part (12) threadedly attached to the male screw part (9) and provided at a base end of a hole part (11), and a housing space part (E) with a constant diameter section (14), a stepped section (15), and a tapered section (17) with reduced-diameter tip provided at an intermediate area of the hole part (11);
• and
• a stop ring (3) fitted in the housing space part (E), including a base-end pressure-contacting slope surface (32) contacting the slope surface (5) with reduced-diameter tip under pressure, and having a tip provided with a plastically-deformable and substantially cylindrical thin part (35) and a pipe extraction preventing tooth part (36) formed at a tip head (37) of the substantially cylindrical thin part (35), wherein
• the tooth part (36) includes a back tooth (36B) and a front tooth (36F) arranged at an interval (W36), the back tooth (36B) has a trapezoidal or substantially trapezoidal sectional shape with a linear first tip side (41) as an upper side, and the front tooth (36F) has a trapezoidal or substantially trapezoidal sectional shape with a linear second tip side (42) as an upper side, and
• as the cap nut (2) threadedly moves forward, the first tip side (41) of the back tooth (36B) and the second tip side (42) of the front tooth (36F) of the stop ring (3) come into a state of tightly contacting an outer peripheral surface (10A) of a straight tip part (10) of a connection target pipe (P) under pressure to generate pipe extraction resistance (Z) and to exert hermetic action on a fluid,
• the tapered section (17) with reduced-diameter tip of the cap nut (2) is inclined so that a diameter of the tapered section (17) with reduced-diameter tip decreases toward a tip of the cap nut (2),
• the slope surface (5) with reduced-diameter tip of the flare joint body (1F) is inclined so that a diameter of the slope surface (5) with reduced-diameter tip decreases toward a tip of the flare joint body (1F),
• the base-end pressure contacting slope surface (32) of the stop ring (3) is inclined so that a diameter of the base-end pressure contacting slope surface (32) increases toward a base end of the stop ring (3) at a radially outside of the slope surface (5) with reduced-diameter tip,
• the stop ring (3) has a cylindrical base outer diameter part (24) between the base-end pressure contacting slope surface (32) and the substantially cylindrical thin part (35) in the axial direction of the stop ring (3),
• the base outer diameter part (24) is slidably fitted to the constant diameter section (14) of the cap nut (2), the straight tip part (10) of the connection target pipe (P) is inserted inside the base outer diameter part (24), and in a pipe connection finished state, a gap in a radial direction between the constant diameter section (14) of the cap nut (2) and the straight tip part (10) of the connection target pipe (P) is filled by the base outer diameter part (24).