Heat exchangers contribute significantly to many energy conversion processes. Applications range from power production, petroleum refining and chemicals, paper and pharmaceutical production, to aviation and transportation industries. A large percentage of world market for heat exchangers is served by the industry workhorse, the shell-and-tube heat exchanger. Recent developments in other exchanger geometries have penetrated in various industry applications; however, the shell-and-tube exchanger by far remains the industry choice where reliability and maintainability are vital. Over the years, significant research and development efforts are devoted to better understand the shell-side geometry. New geometries are introduced for performance enhancement and to improve reliability. The pioneering work published by J. Nemcansky et al. in the Trans. Institute of Chemical Engineers in May, 1990, on helical baffles paved the way to a major shift from a conventional understanding of baffles in a shell-and-tube heat exchanger. Helical baffles serve as guide vanes for shell-side flow as compared to creating flow channels with conventional segmented baffles. In the past decade, ABB Lummus Heat Transfer has extended the understanding of the helical baffle geometry through extensive testing and development. CFD flow simulation studies have further confirmed the helical baffle advantage. Industry feedback on operating Helixchanger (R) heat exchangers - the shell-and-tube heat exchangers with helical baffles - has demonstrated low fouling characteristics as well as a higher conversion of shell-side pressure drop to heat transfer. In this paper, the characteristics of this novel Helixchanger heat exchanger are discussed. Examples from early installations in the power industry to the major applications in the petro-chemical and refining industries are presented, illustrating the advantages in reducing fouling and increasing reliability while achieving lower total life cycle costs.