The main part of the conical head cone under internal pressure, the maximum stress occurs at the end of the film. At the joint of the cone and the cylinder, because of the geometrical discontinuity and the sudden change of the curvature radius, the lateral thrust will be produced, causing greater edge stress and bending. Therefore, it needs to be strengthened. In the end, the axial bending stress is the main controlling factor, which is two times of stress, so the stress intensity control; on small end, because of stress at the junction of the small end and the cylinder is mainly the average circumferential stress and radial stress of local membrane stress, so stress the strength can be controlled, but due to the local film stress range beyond the edge effect, for the sake of safety, the stress intensity control within the. In the end, in any case strengthen section thickness is not less than the thickness of conical shell is connected, strengthen the length should not be less than the length of the cylinder, strengthening should be not less than. For the small end, the thickness of the strengthening section shall not be less than the thickness of the conical shell to be connected in any case, and the length of the conical shell shall not be less than that of the conical shell, and the length of the strengthening section of the cylinder shall be no less than.