Despite more than 15 years of operational reliability, a 317L (UNS S31703) stainless steel steam surface condenser at a power plant in the Northeastern United States was revealed to have a significant waterside pitting corrosion problem. The pitting was identified during Eddy Current testing and verified by removing sample tubes. The severe pitting in the tubes was primarily focused at the seam weld region. Possible causative factors for the pitting attack were identified. Metallography and electrochemical testing confirmed non-optimal corrosion resistance along the original laser seam welds, as compared to the base metal. Modifications to the cooling water chemistry were instigated to reduce the severity of the pitting attack in an effort to extend the service life of the condenser bundle. Re-tubing options with alternative stainless steel alloys are also discussed.

Subject
Seams, Water, Tubes, Sulfates, Acidity, Condensers, Tubing, Pitting, Corrosion resistance, Cooling water, Stainless steel, Chlorides, Fouling
Keywords:
Pitting, Seam Weld Corrosion, Steam Condenser, 317L (UNS S31703), Stainless Steel, Cooling Water
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2022
Association for Materials Protection and Performance (AMPP)
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