A Dimple Jacket is a thin external shell secured to the main vessel by a series of uniformly spaced button welds. The heating or cooling fluid is circulated through the dimple jacket to affect the temperature of the contents in the main vessel. The jacket is normally coved with an insulating material to optimize the efficiency of the heat transfer. Dimple jackets are normally applied in zones dictated by the width of the dimpled plate. Dimple jackets are often utilized in conditions with low to moderate temperature differential, and gradual heating or cooling. Dimple Jackets can be applied to heads or shells.