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U.S. Department of Energy
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Causes of denting. Volume 4. Isothermal capsule tests. Final report

Technical Report ·
OSTI ID:5282183
Inconel 600 tube deformation and carbon steel corrosion rates have been determined in a variety of chemical environments under isothermal conditions. The contaminants studied were some of those which could occur during deviations from recommended steam generator operating conditions. Acidic chloride solution is the contaminant which produces the linear (or accelerated) corrosion associated with tube deformation, or denting. The threshold pH and Cl/sup -/ concentration limits for linear attack which is morphologically characterized by nonprotective magnetite (laminated structure) is between 0.005 and 0.02 N Cl/sup -/ (175 to 700 ppM Cl/sup -/) and at a pH of approx. 4. Corrosion rates at this threshold chemistry are typically about 1 mpy. At higher concentrations, greater than or equal to 0.05 N (1750 ppM) Cl/sup -/, sufficient nonprotective magnetite forms to produce tube deformation. Other contaminants had a minor effect (SO/sub 4//sup =/) or little or no effect (SiO/sub 2/, NiO, or CuO). Corrosion rates for 405 SS were 2 to 3 times less than for carbon steel and were not characterized by nonprotective magnetite nor tube deformation. Minor pitting of the Inconel tube wall was found on some of the specimens.
Research Organization:
Westinghouse Electric Corp., Pittsburgh, PA (USA). Research and Development Center
OSTI ID:
5282183
Report Number(s):
EPRI-NP-3275-Vol.4; ON: DE84920264
Country of Publication:
United States
Language:
English