The tee is the most difficult product to make in the pipe fittings. The main difficulties are that the height and inner diameter R of the branch pipe are small, and the wall thickness of the shoulder is 1.4 times larger than that of the straight pipe. These three difficulties are all overcome by Bohai Heavy Industry. The length of the branch pipe and the main pipe is the same, the wall thickness of the ridge is more than 1.5 times that of the main pipe, and the inner arc R≤80°. This process is not limited by the material, any material pipe can be made.