ESDU 87030 introduces the essential features of "pinch technology" or process integration used to optimise energy utilisation in a process plant. The network design techniques are incorporated into the computer program INTEGRITY (see ESDU 00043). After reviewing the basic concepts, the method is explained by which energy targets are defined in advance of the process design being finalised. The use of the targets as a guide to designing an energy efficient process is described, together with the significance of the pinch in selecting heat exchange matches between hot and cold streams. Cost-targeting and a systematic approach to design optimisation through capital/energy trade-offs are introduced. A brief discussion also considers selection of combined heat and power systems, opportunities for heat pumping, and the position of separation systems in relation to the pinch. The most common pitfalls and errors in the use of the techniques are highlighted and at each stage in the discussion the key points are illustrated by practical numerical examples from a real case study. Finally, the case study is the subject of a detailed discussion to show how relaxing some of the rules established for process integration can result in large savings in capital cost in exchange for quite small increases in energy consumption in comparison with the optimum.