Patent ID: 8152205

Claim:
A connection, comprising: a resin tube ( 9 ); a stainless-steel fitting main body ( 1 ) having an insert part ( 8 ); a sleeve ( 2 ); and a nut ( 3 ), wherein the insert part ( 8 ) has a male screw part ( 7 ) and a generally cylindrical shape with an outer surface having an outer diameter which is about the same as an inner diameter of the resin tube ( 9 ), the insert part ( 8 ) further having a protrusion part ( 8 a ) formed with a trapezoidal quarter section in a circumferential direction near the protrusion part's center, the protrusion part ( 8 a ) having an outer diameter which is larger than said outer surface, said insert part ( 8 ), said protrusion part ( 8 a ) and said fitting main body ( 1 ) being a single piece, the sleeve ( 2 ) having an inner surface having an inner diameter which is larger than an outer diameter of the resin tube ( 9 ), said insert part ( 8 ) being inserted into said resin tube ( 9 ) such that a surface of the protrusion part ( 8 a ) contacts the resin tube ( 9 ) such that the resin tube ( 9 ) is pressed between the protrusion part ( 8 a ) and the sleeve ( 2 ) and locked to the fitting main body ( 1 ), said nut ( 3 ) being screwed onto the fitting main body ( 1 ) and moving the sleeve ( 2 ), whereby the resin tube ( 9 ) is pressed and locked between the insert part ( 8 ) and sleeve ( 2 ), a step part, composed of a first diameter part ( 2 a ) and a second diameter part ( 2 b ) smaller than the first diameter part, being formed on an outer surface of the sleeve ( 2 ), the length of said second diameter part ( 2 b ) being such that an end-face of the second diameter part ( 2 b ) protrudes outward from said nut ( 3 ) when the sleeve ( 2 ) is inserted into the nut ( 3 ), the nut ( 3 ) and the sleeve ( 2 ) are integrated by pressing and spreading an inner diameter of said end-face, and the protrusion part ( 8 a ) and the first diameter part ( 2 a ) are opposing when in contact with a side-face of a wrench hooking part in the fitting main body.