This Screw Plug Immersion Heater consists of a tubular element welded or brazed into a threaded screw plug which can be inserted into a threaded opening in a tank wall or through a mating full or half coupling. Features Steel construction. Fluid heat transfer media, tar, high to low viscosity petroleum oils, asphalt, wax, paraffin, degreasing solvents, alcohol, molten salt, and other solutions not corrosive to steel. Can handle temperatures to 750 degrees F.