The possibility for formation of macro-cell corrosion in a liquid with low electrical conductivity / M. Matsumura in Materials and corrosion, Vol. 62 N° 5 (Mai 2011)  

Public ISBD [article]  inMaterials and corrosion > Vol. 62 N° 5 (Mai 2011) . - pp. 449–453 Titre : The possibility for formation of macro-cell corrosion in a liquid with low electrical conductivity Type de document : texte imprimé Auteurs : M. Matsumura, Auteur Année de publication : 2011 Article en page(s) : pp. 449–453 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon steel pipe Flow accelerated corrosion Macro-cell Micro-cell Mihama nuclear power plant Pure water Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The possibility of electrochemical corrosion of carbon steel at the rate of 3.25 × 10−5 A/cm2 in water was examined under the conditions present during an accidental pipe rupture at the Mihama nuclear power plant: liquid conductivity, 7.5 µS/cm; dissolved oxygen concentration, 5 ppb or less; pH 8.6∼9.3; ferrous ion concentration, 20 ppb or less; temperature, 142 °C. The corrosion rate of iron in a micro-cell with a dissolved oxygen reduction cathode was estimated to be only 1/400 of the preceding rate. On the other hand, that in a micro-cell with a hydrogen ion reduction cathode was estimated to be as high as 1/10 of the preceding rate, that is, 3.25 × 10−6 A/cm2. Two important factors may have influenced the corrosion rate: the remarkable wall thinning, which must have been the direct cause of the rupture of the pipe, was located close to, and downstream from, an orifice; and, the water temperature was in the range at which carbon steel makes a transition from the active to the passive state. Taking these facts into consideration, it appears possible that micro-cells with different corrosion rates might be generated and integrated into a macro-cell, where the iron dissolution rate might be accelerated to as much as 10 times that of the micro-cell. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905573/abstract [article] The possibility for formation of macro-cell corrosion in a liquid with low electrical conductivity [texte imprimé] / M. Matsumura, Auteur . - 2011 . - pp. 449–453. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 5 (Mai 2011) . - pp. 449–453 Mots-clés : Carbon steel pipe Flow accelerated corrosion Macro-cell Micro-cell Mihama nuclear power plant Pure water Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The possibility of electrochemical corrosion of carbon steel at the rate of 3.25 × 10−5 A/cm2 in water was examined under the conditions present during an accidental pipe rupture at the Mihama nuclear power plant: liquid conductivity, 7.5 µS/cm; dissolved oxygen concentration, 5 ppb or less; pH 8.6∼9.3; ferrous ion concentration, 20 ppb or less; temperature, 142 °C. The corrosion rate of iron in a micro-cell with a dissolved oxygen reduction cathode was estimated to be only 1/400 of the preceding rate. On the other hand, that in a micro-cell with a hydrogen ion reduction cathode was estimated to be as high as 1/10 of the preceding rate, that is, 3.25 × 10−6 A/cm2. Two important factors may have influenced the corrosion rate: the remarkable wall thinning, which must have been the direct cause of the rupture of the pipe, was located close to, and downstream from, an orifice; and, the water temperature was in the range at which carbon steel makes a transition from the active to the passive state. Taking these facts into consideration, it appears possible that micro-cells with different corrosion rates might be generated and integrated into a macro-cell, where the iron dissolution rate might be accelerated to as much as 10 times that of the micro-cell. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905573/abstract

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