Hemispherical head (Hemispherical)
Mechanically the most efficient shape, but the most expensive to make
A hemispherical head is exactly half of a sphere: its radius (CR) is half the vessel's inside diameter (0.5×Di) and its depth (DH) is exactly the same radius. This head has no separate knuckle because its whole surface is one uniform curvature, just like the body of a spherical vessel.
What is a hemispherical head?
A hemispherical head is exactly half of a sphere: its radius (CR) is half the inside diameter of the vessel and its depth is exactly the same radius. This head has no separate knuckle, because its whole surface is one uniform curvature.
This uniformity means the stress from internal pressure is spread evenly, so for a given pressure it needs the least thickness of all head types; in return, forming it is more expensive than for shallower forms.
Geometry formulas of the hemispherical head
The hemispherical geometry has the simplest and at the same time the strongest relation:
If the design pressure is so high that an elliptical or torispherical thickness becomes impractical, the cost of forming a hemisphere is justified by the plate saving.
Online calculation
See the head's dimensions, volume and weight for a real diameter and thickness
Hemispherical head (Hemispherical)
Liquid level and volume inside this head
How the head is mounted
Development of this head (flat blank before forming)
The diameter of a flat plate of the same thickness and material that weighs the same as the formed head — an initial workshop estimate based on equal weight, not allowing for thickening or extra stretching at the knuckle.
The vessel head production process
From calculating the blank diameter to final edge preparation — the steps of making a vessel head in the workshop
Calculating the blank diameter
Cutting a disc from plate with the diameter and thickness calculated for the head type and vessel diameter
Cutting the plate blank
Precise cutting of steel or stainless plate by plasma, laser or gas according to the technical drawing
Pressing the head
Hot or cold forming of the disc with a die and industrial press until it reaches the final head profile
Edge preparation
Machining the edge, bevelling and preparing the weld area for fitting to the vessel shell
Video coming soonChoosing a head: the balance between pressure, cost and time
If the design pressure is so high that the thickness needed for elliptical or torispherical heads becomes impractical (very thick plate, high weight and transport cost), the extra forming cost of a hemisphere is economically justified by the plate saving.
Gallery of heads we have made
Hemispherical head gallery
Applications and industries served
Buying heads from Behineh Ab
Six steps from first contact to delivery
Give the outside diameter, plate thickness, head type and required material.
The calculated weight, unit price and delivery time are sent the same business day.
Plate is supplied with the mill certificate and inspected on arrival before cutting.
Cutting the disc, hot or cold pressing depending on thickness, and checking dimensions with a template.
Machining the cylindrical edge and bevelling it ready for welding to the shell.
Packing, issuing the part identification sheet and shipping nationwide.
What sets us apart
Price inquiry
vessel head
Enter the diameter, thickness and head type; you will receive the calculated weight and unit price.
- Quotation with the exact weight of the part
- Standard heads delivered in 7 business days
- Shipping nationwide
