FAC Mitigation and Cycling Scenarios Without Financial Investment

ABSTRACT

Flow-accelerated corrosion (FAC) has been identified as the main cause of damage, failures, and unavailability in heat-recovery steam generators (HRSGs), leading to multimillion-dollar losses from repairs and lost revenue. Across utilities worldwide, FAC is the most frequently cited HRSG tube-damage mechanism (≈ 13 %), exceeding pitting and hydrogen damage.

During recent plant outages at the Genelba Combined Cycle Power Plant of Pampa Energía, Marcos Paz, Buenos Aires, Argentina, FAC was observed in various areas of the HRSG, mainly in downcomers, risers, cyclone separators, and deflectors. This type of corrosion occurs in zones with temperatures ranging from 115 °C to 200 °C, inadequate pH, and low oxygen availability.

This paper explains how Pampa Energía optimized its chemistry program (all-volatile treatment, under oxidizing conditions) by reinforcing low-pressure drum pH control and introducing controlled low-level oxygen injection, approaching mild oxygenated treatment conditions without fully changing the treatment program. The optimized chemistry program significantly mitigated FAC without additional capital investment.

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