Heating or cooling of a fluid by another is made in a heat exchanger with heat dissipation from surfaces of the equipment. Over time, the abundant quantity of impurities promotes fouling in a heat exchanger. This equipment has extensive domestic and industrial applications. The concepts of design, operation, and maintenance of heat exchanger are available in the form of complete technical literature, but this literature is extensively distributed throughout the industrial bulletins, industrial design codes and standard, technical journals, etc. Thus, the aim of this book chapter is to reveal the concepts design, operation, cleaning, and maintenance of heat exchanger closely related to the industrial practices.