Root Cause Failure Analysis of a Heat Recovery Steam Generator (HRSG) Condensate Preheater Tube

This investigation delves into the metallurgical root cause failure analysis of a leaking heat recovery steam generator (HRSG) condensate preheater tube from a combined cycle power plant. The CPH tube experienced failure in the form of multiple pinholes, resulting in leakage. Detailed visual examination, dimensional measurements, metallographic examination, hardness testing, chemical analysis, EDS analysis and x-ray diffraction analysis elucidated the damage mechanism as acid dew point corrosion. Findings indicated severe corrosion attack by sulfuric acid formation on the tube's exterior, corroborated by the presence of iron sulfate in deposits and high sulfur content. Furthermore, recommendations were also given to avoid the recurrence of similar failures.