Arc surface sealed pipe joint for rail wagon

The invention relates to a rail wagon braking device, in particular to a pipe joint for the rail wagon braking device. The pipe joint comprises a threaded joint body, an arc surface joint body and a nut. The key technology of the pipe joint is that the threaded joint body is provided with a first outer arc surface, the arc surface joint is provided with an inner arc surface and a second outer arc surface, the unthreaded end of the nut is pressed against the second outer arc surface of the arc surface joint body, and the threaded end of the nut is joined with threads of the threaded joint body. The arc surface sealed pipe joint has the advantages that due to the arc surfaces of the threaded joint body and the arc surface joint body, the threaded joint body and the arc surface joint body can be relatively rotated at an angle of 0 to 2.2 degrees in a cavity body formed by the nut and the threaded joint body, a big included angle of not more than 2.2 degrees can exist between two adjacent pipes to offset a part of external force deforming the pipes, requirements of pipe assembly for coaxiality are relatively low, and two adjacent pipes can automatically finely adjust the included angles to reduce counter force in heavy load working condition.