The Hemispherical also becomes the Semi-Spherical Head, which is the head formed by the crown part of the spherical shell. There are  Semi-Spherical Head and Non-Flanged Spherical Head.Pressure vessel mostly used Hemispherical head as the head, Its advantages are the minimum surface area under the same volume and the thinnest thickness required under the same pressure condition, look from the save material and strength, is the most reasonable.Usually used in high pressure vessels.The unflanged spherical head is connected to the simplified body with an Angle weld, which is commonly used as the middle head of two independent pressurized Chambers in the container, or as the end head.