Indirect heaters are provided to increase the temperature of the crude oil if it is highly viscous or has a high pour point or there is potential hydrate formation. This heating will prevent plugging (due to temperature reaching below crude oil pour point) at any downstream point equipment. The process fluid to be heated flows through a pipe coil mounted in the upper half of the unit. Potable water/Glycol, can be used as the source of heat. The bath is heated by a direct fired burner. The lower portion is fitted with forced draft burner. The fuel for the burner can be either diesel or conditioned fuel gas. During black start-up, diesel will be used as the fuel source for burner and once the process system is lined-up, then the diesel can be switched with fuel gas which can be tapped from separator gas outlet upon availability. The duty provided by the heater and increase the water temperature to approximately 60°C to 85°C. Since the shell is operates at atmospheric pressure, the max temperature of the water bath should be limited to 90°Cto prevent water vapour losses. To achive higher temperatures, more than 100°C, of process fluid, glycol bath may be used instead of water.