Caustic corrosion also referred to as “Caustic attack” or “Caustic gouging” generally results from the fouled heat transfer surfaces on boiler tubes and due to the presence of sodium hydroxide in the boiler water. Once the caustic concentrations reached a certain level the caustic attack occurs and results in irregular wall thinning or gouging of the tube water side surface. The damage progresses through the tube wall until it ruptures. Such caustic corrosion failure was observed in one tube from a utility’s boiler. This paper presents the laboratory metallurgical analysis of the failed tube including welds and the process fluids and its effects on the caustic corrosion. The laboratory analysis includes chemical analysis, scale deposit analysis, metallography, and hardness tests.

Subject
Energy dispersive X-ray spectroscopy, Water, Perforation, Grooves, Metal surfaces, Tubes, Walls, Hematite, Failure analysis, Boilers, Oxygen, Copper, Deposit corrosion
Keywords:
Caustic corrosion, boilers, high temperature corrosion, tubes, failure analysis
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2022
Association for Materials Protection and Performance (AMPP)
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