Failure of heat exchangers installed in industrial facilities may lead to serious accidents resulting in injuries, environmental spills, and significant financial losses. The purpose of this section is to discuss various design choices that may work properly for most typical operations but fail when heat exchangers operate at unexpected operating conditions which were not considered at the design stage. In this section, five different design choices that could lead to serious operational problems are described in detail:

• Selecting design temperatures for the heat exchangers installed in networks that are subject to non-uniform fouling (Sec. A)
• Selecting design temperatures for electric process heaters (Sec. B)
• Selecting fixed tubesheet heat exchangers without considering all possible operating cases (Sec. C)
• Selecting conventional heat exchanger geometry for cycling services and high tube-side temperature increase (Sec. D)
• Selecting the tube bundle geometry resulting in unforeseen flow-induced vibration tube failures (Sec. E).

Several industrial case studies are used to illustrate the key messages of each section and to highlight some of the limitations in the current methodologies, accepted practices, and industry standards in heat exchanger design. Moreover, it is shown that selecting designs that avoid operational issues do not necessarily result in the more expensive solutions.