2. CYLINDRICAL STORAGE VESSELS

Cylinders are widely used for storage due to their being less expensive to produce than spheres. However, cylinders are not as strong as spheres due to the weak point at each end.

This weakness is reduced by hemispherical or rounded ends being fitted. If the whole cylinder is manufactured from thicker material than a comparable spherical vessel of similar capacity, storage pressure can be similar to that of a sphere.

Figure 36

ULLAGE -The 'Ullage' space is the vapour space above a liquid in a storage vessel and is necessary to allow for expansion of the liquid during hot weather. The amount of ullage space depends on the density of the liquid, particularly volatile liquids and is usually increased with increase in liquid density.