Abstract Pervasive tube failures in heat-recovery steam generators (HRSG) have severely impacted performance and efficiency. Several fundamental failure mechanisms have been identified and their metallurgical causes are well understood. However, current practice to increase the thermal efficiency and flexibility of HRSG operations has contributed to these tube failures. Substantial rises in flue gas temperature, units designed for base load operation switched to cyclic load units, and more aggressive start-up loading rates are just some of the constant demands placed on HRSG’s. In this report, case histories are presented which illustrate the common HRSG failure modes that can occur as a consequence of the increasingly demanding service.