Heat exchangers can be made more compact by either enhancing the heat transfer coefficient or by increasing the amount of area per unit volume. The use of low-finned tubes is an effective means of achieving the latter. The extent to which the equipment size can be reduced using such means is problem-dependent. Decisions of whether or not to employ process intensification have to be made at the conceptual stage of design. There ist therefore, a need for sizing procedures that avoid the recourse to full detailed design. Such a procedure is reported here. The key to the procedure is a relationship between the shell-side pressure drop, shell-side heat transfer coefficient and overall exchanger surface area. The procedure has been applied to a number of ＇typical＇ fluids. The results are presented in a series of charts relating exchanger size and duty. It is shown how individual duties can be ＇normalized＇ in the form of a ＇duty factor＇ that relates shell-side pressure drop, mass flow rate, stream temperature change and exchanger temperature driving force. So, the charts are independent of duty.