Hemispherical (hemi) heads are the strongest of the formed heads. They can resist about twice the pressure rating of an elliptical dished head or cylindrical shell of the same thickness and diameter. Due to their strength and resistance, these tank heads are widely used for the storage of liquids and gasses under pressure. A hemi head is frequently employed in large-diameter or high-pressure applications when space is limited. Hemispherical is the ideal shape for development of hemispherical dish end, because the pressure in the vessel is divided equally across the surface of the head.