What is a Pressure Vessel Head?

What is a pressure vessel head ? A head is one of the end caps on a cylindrically shaped pressure vessel.

The inward pressure of each type of head determines the range of its use.

The first type is elliptical head or named ellipsoidal head, the circumferential and meridional stresses of this type of head are not constant on the shell, but vary at all points, for example, the circumferential and axial stresses at the apex are equal, while the stresses at the equator are different. while the stress on the equator is different. If the internal pressure on the head is relatively uniform, the axial stress is constant as tensile stress, decreasing gradually from the maximum value at the apex to the minimum value at the equator.

Since the shallower the head is, the higher the value of compressive stress at the edge of the head is, so when we make the head, we generally limit the ratio of long and short axis of the head to 2.6.

The requirements for the thickness of the head are all under the premise of satisfying the strength, and for some large diameter thin-walled ellipsoidal heads, the requirements of his stiffness are also considered.

The second type is Torispherical Head, which is a kind of head composed of three parts: spherical part, straight edge section and transition zone. The magnitude of the edge stress of the disc-shaped head is related to the ratio of the radius of the transition zone to the radius of the sphere.

And it is inversely proportional, that is, the smaller the ratio is, the stronger the curvature border mutation is, and the higher the edge stress is. So and in order to reduce the edge stress of butterfly head, it will design the over zone on the head.

The third kind is Hemispherical Head, this kind of head can generally only be used for occasions where the pressure is not high, mainly because the radius of its curvature will change abruptly at the connection between spherical surface and cylinder.

At the same time, transverse thrust exists because there is no common tangent between the two shells, so considerable discontinuous stress is generated. This also determines that the fillet weld between the head and the cylinder must be of full weld-through construction.

The last point is the conical head. Take the conical head subject to internal pressure without folded edge, its main part is under internal pressure and the maximum film stress occurs at the big end. where the cone and cylinder parts are connected.

Due to geometrical discontinuity and abrupt change in radius of curvature, a large transverse thrust will be generated at this place, causing a large edge stress and prone to bending phenomenon

Hunan Jetvision is one of the leading heat exchanger manufacturers and suppliers with over 20years experience of vessel heads production and technology, we mainly manufacture, stock and supply Elliptical Head, Hemispherical Head, Torispherical Head, etc. at the best factory prices.