The dished only head is also called the spherical head without folding edge. The dished only head is a part of the spherical head directly connected to the cylinder. It has a simple structure and is easy to manufacture. It is often used as the middle head of two separate pressure chambers in the container, and can also be used as an end cover. The fillet weld at the connection between the head and the cylinder should adopt a full penetration structure. The radius of curvature changes suddenly at the connection between the spherical head and the cylinder. There is a lateral thrust because the two shells have no common tangent line, so a considerable discontinuous stress is generated. This head can generally only be used in low pressure occasions.