Electric heaters on threaded plugs are especially made for heating liquids for both multiple industrial and civil applications. They are designed to be inserted into pipes, tanks or pressure vessels and to be immersed directly in contact with the fluid. This type of heater is composed of a tube bundle of 1, 2 or 3 elements (three-phase) welded on a brass or stainless steel threaded fitting suitable for fixing to the wall of the tank to be heated. The flange heaters are made up by several electric heating elements of different diameters joint in one bundle. Each heating element is welded on unified flanges DIN, ANSI. Electrical connections are placed inside standard IP40, IP55, IP65, IP68 junction boxes or inside o specific explosion-proof junction boxes for use in explosive atmospheres.