A tank head is a conical steel component forming the top or bottom closure of a storage tank. It is manufactured by developing a flat plate into a conical blank and subsequently welding the plate into its conical form. The resulting geometry corresponds to that shown in the reference photograph.

 

Once the cone has been welded to its final shape, the straight conical shell is cold‑formed at the perimeter, i.e. at the junction where the head connects to the tank shell. This edge is typically bent to a radius of R 30–60 mm. The purpose of this forming operation is to achieve a uniform structural transition, improved load distribution, and reliable weldability at the shell‑to‑head interface.

The conical tank heads shown in the reference image represent the top and bottom heads of atmospheric (non‑pressurised) tanks with diameters in the range of 1…10 m.

For atmospheric service, the top head can be sized to carry the weight of a person using a straightforward assessment method. Owing to the inherent stiffness of the conical geometry, even a 10‑metre‑diameter top head may remain unreinforced: the cone will deflect locally under a walking load and subsequently return to its original shape without permanent deformation.

Many tanks, however, incorporate a mechanical agitator, which introduces both vertical loading and torsional moments into the top head. The agitator may be located centrally or near the shell‑to‑head junction. In such cases, the structural capacity of the top head must be verified separately to ensure that it accommodates the actual load conditions.

Scaling behaviour and increase in surface area

As the tank diameter increases, the surface area of the head grows with the square of the diameter. This affects:

- loading
- material massn
- structural stiffness