Hemispherical head

A hemispherical head is a head consisting of a hemispherical shell and a straight edge (short section of a cylinder). The curvature radius of the spherical shell is equal and the force is uniform. Compared with other heads, the hemispherical head needs the smallest wall thickness under the same internal pressure. At the junction of the spherical shell and the cylinder with the same thickness, the edge stress caused by the change of curvature radius is only 3.1% of the total membrane stress of the cylinder, which can be neglected. Therefore, the mechanical properties of the hemispherical head are the best and the materials used are the most economical.

The axial section of hemispherical head shell is hemispherical 3~book hemispherical head i-spherical crown, 2-trapezoidal spherical plate 231 cylinder. The hemispherical head with smaller diameter can be formed by integral pressing, but the larger diameter is difficult to be pressed because of its larger penetration. Therefore, several trapezoidal spherical petals of the same size and a circular spherical panel (spherical crown) at the top center need to be welded together. The structure of the head is shown in the diagram. Compared with other types of head, the hemispherical head has the smallest thickness, the smallest surface area and the least material consumption under the same diameter and pressure. The force is uniform. However, due to manufacturing difficulties, other vessels are seldom used except for pressure vessels with higher pressure and larger diameter.