Each ControHeat® jacket is cast from ASTM B179 Grade A 356 copper-free aluminum to fit any piping component. CSI maintains a pattern library for over 10,000 components, and new patterns can be made for almost any application. A carbon steel or stainless-steel pressure chamber is embedded in the aluminum casting to contain the heating medium. This casting is not designed to hold pressure, as it only promotes uniform heat transfer around the piping component. A thin layer of heat transfer compound is applied to the inside of the ControHeat® piping jacket to promote even heat transfer between the aluminum jacket and the component.