Torispherical head is a type of end cap used on pressure vessels and storage tanks, characterized by its unique shape that combines a spherical dome with a toroidal (doughnut-like) edge. This shape is created with two main curves:

1. Crown Radius: The main, central part of the head has a larger spherical radius, called the crown radius, which forms a slightly curved, dome-like center.

2. Knuckle Radius: The outer edge has a smaller radius, called the knuckle radius, which curves sharply and connects the dome to the cylindrical body of the vessel. This toroidal section forms a rounded edge, or “knuckle,” where the head meets the vessel shell.

The torispherical shape is designed to contain pressure, though the knuckle region can experience higher stress concentrations than in elliptical or hemispherical heads. As a result, torispherical heads are commonly used in vessels with low to moderate pressure requirements and are typically easier and more cost-effective to manufacture compared to fully hemispherical or elliptical heads.