Sealing self-locking type flange welding nut

The utility model discloses a sealing self-locking type flange welding nut which comprises a lower nut body and a first internal thread, the first internal thread is machined in the lower nut body, and a self-locking device is installed above the lower nut body. According to the sealing self-locking type flange welding nut, a convex part can be machined on the upper portion of the lower nut, a concave part is machined on the lower portion of the interior of the upper nut, and therefore after the lower nut and the upper nut are sequentially installed on a bolt, the inner wall of the convex part on the lower nut can be attached to the inner wall of the concave part on the upper nut; therefore, the self-locking effect of the self-locking nut is improved through mutual matching of the concave part and the convex part, a sealing ring can be arranged at the circular groove of the flange plate, then a flange gasket is installed below the sealing ring, the sealing performance of the connecting position can be improve