Abstract: A method for heating crude oil to be processed in a petrochemical installation, comprises successive heat exchangers disposed in series, each heat exchanger using pressurized steam as the heating fluid. Each exchanger has a lower exchange chamber, a liquid product supply line and a tube bundle, the steam transferring heat to liquid product flowing through the tube bundle. Each heat exchanger comprises an upper separation chamber disposed above the lower exchange chamber, the separation chamber having a gas phase outlet and a liquid phase outlet, the liquid phase outlet being disposed lower than the level at which the tube bundle extends into the separation chamber. Successive heat exchangers are connected together by a pipe communicating between the liquid phase outlet of the upper separation chamber of one of the heat exchangers and the liquid product supply line of the next heat exchanger.