US Patent 9791084 Pipe joint made of synthetic resin

A pipe joint made of synthetic resin includes: a joint body including a male screw portion on an outer circumferential portion; and a union nut including a female screw portion formed on an inner circumferential portion such that the female screw portion is tightened onto the male screw portion of the joint body. An outer circumferential surface of the joint body has a projection portion that is integrated therewith and projects radially outward. An inner circumferential surface of the union nut has a convex or concave engagement portion that is integrated therewith and engages with the projection portion when the union nut is tightened up to an appropriate position.