Water bath indirect heaters have a long history of successful application in the oil and gas industry. They have been applied to a variety of operations ranging from the heating of natural gas to the heating of sour crude. The heater consists of three basic elements: the firebox, shell and flow coil. These elements are carefully designed for each standard size. The firebox is designed to rapidly transfer the heat released by the burning fuel to the water bath. The flow coil is designed to safely contain the process fluid and transfer the required heat from the water bath to the process streams. A variety of coils is available for each firebox size, to allow a selection for the most economical and efficient combination.