Vessel head

Vessel head ends are mostly used in storage or pressure vessels in industry:pharmaceutical, chemical, biotech, cryogenic, municipal water treatment, propane, extraction, and food/beverage industries. These ends, which in upright vessels are the bottom and the top, use less space than a hemisphere (which is the ideal form for pressure containments) while requiring only a slightly thicker wall..


The shape of the heads used can vary. The most common head shapes are:

Hemispherical head

A sphere is the ideal shape for a head, because the stresses are distributed evenly through the material of the head. The radius (r) of the head equals the radius of the cylindrical part of the vessel.

Ellipsoidal head

This is also called an elliptical head. The shape of this head is more economical, because the height of the head is just a fraction of the diameter. Its radius varies between the major and minor axis; usually the ratio is 2:1.

SemiĘCEllipsoidal Dished Ends

2:1 Semi-Ellipsoidal dished heads are deeper and stronger than the more popular torispherical dished heads. The greater depth results in the head being more difficult to form, and this makes them more expensive to manufacture. However, the cost is offset by a potential reduction in the specified thickness due to the dished head having greater overall strength and resistance to pressure.

Torispherical head (or flanged and dished head)

These heads have a dish with a fixed radius (r1), the size of which depends on the type of torispherical head.The transition between the cylinder and the dish is called the knuckle. The knuckle has a toroidal shape.

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