Fastening device for single-side small-angle flange connection and fastening method

The invention discloses a fastening device for single-side small-angle flange connection and a fastening method. The fastening device comprises a bolt matched with a screw hole in a small-angle flange; and the fastening device furthermore comprises a screw head installed on the head of the bolt and an opening gasket matched with the bolt, wherein the outer diameter of the screw head is smaller than the inner diameter of the screw hole, the opening inner diameter of the opening gasket is smaller than the outer diameter of the screw head, and the outer diameter of the opening gasket is larger than the inner diameter of the screw hole. By means of the fastening device, the bolt can reversely insert and penetrate through the screw hole from the right-angled flange end, the bolt is limited through an opening flange, then the bolt is screwed tightly and fixed through a nut, and the problem that flange strength is lowered due to the fact that positive-inserting from the small-angle flange end needs a kidney-shaped s