Pitting Corrosion

Strehblow, Hans‐Henning

doi:10.1002/9783527610426.bard040402

Cited by 7 publications

(7 citation statements)

References 49 publications

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“…The high solute concentrations and DO of the absorber unit fluids makes them aggressively corrosive solutions, and may give rise to severe pitting corrosion, which has been reported for FGD structures (including systems evaluated in this study) and is often associated with MIC (Franklin et al, 1991; Strehblow, 2007; Moskal, 2011). The FGD units at Facility A have not yet experienced serious corrosion problems, but Facility B units have experienced severe problems with corrosion, despite the fact that both units were constructed using the same type of steel.…”

Section: Discussionmentioning

confidence: 64%

Microbial communities associated with wet flue gas desulfurization systems

Brown¹,

Brown²,

Senko³

2012

Front. Microbio.

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Flue gas desulfurization (FGD) systems are employed to remove SOx gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids (TDS) of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal-fired electricity generation facilities were evaluated using culture-dependent and -independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems.

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Section: Discussionmentioning

confidence: 64%

Microbial communities associated with wet flue gas desulfurization systems

Brown¹,

Brown²,

Senko³

2012

Front. Microbio.

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“…Only in the case of the local attainment of X { ½ s cr will it be possible to initiate corrosion pits and prevent their repassivation. 25,28 It is known that the adsorption ability of halogen ions increases in the order Cl 2 ,Br 2 ,I 2 , which is usually explained by the decrease in hydration energy with increasing ion radius. 24,30,31 This suggests that the bromide ions will attain the critical surface concentration for pitting, X { ½ s cr , at a lower bulk electrolyte concentration by reason of its better adsorption ability relative to the chloride ion.…”

Section: Critical Halide Ions Concentrationsmentioning

confidence: 99%

“…22 The critical concentration of aggressive ions can be connected with the presence at the metal surface of the minimum ion concentration X { ½ s cr necessary to form corrosion pits and to keep them growing. 25,28,29 The surface concentration is depended on the adsorption properties of halide ions. Only in the case of the local attainment of X { ½ s cr will it be possible to initiate corrosion pits and prevent their repassivation.…”

Section: Critical Halide Ions Concentrationsmentioning

confidence: 99%

Effect of halide anions and temperature on initiation of pitting in Cr–Mn–N and Cr–Ni steels

Tzaneva¹,

Fachikov²,

Raicheff³

2006

Corrosion Engineering, Science and Technology

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9 steels in halide solutions (F 2 , Cl 2 , Br 2 and I 2 ) has been investigated. The study involved cyclic potentiodynamic polarisation tests with subsequent examination of the specimens by both optical and scanning electron microscopy. Values of the critical concentrations of halide ions, [X 2 ] cr , beyond which pitting occurs, as well as breakdown potentials for pitting in chloride solution, have been established. In addition, the effect of the temperature over the range of 5-80uC on the critical chloride ion concentration [Cl 2 ] cr has been investigated and it has been found that temperature has a negligible effect beyond 40uC.

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“…The anion adsorption lowers the surface tension of the oxide film (13). It may also promote not only dissolution of the oxide film but also dehydration and crystallization of the film due to complex formation (14,15). Since the oxide film becomes thinner or fragile, they may lead easy crack formation and increase the area of ruptured film, i.e.…”

Section: Ecs Transactions 1 (4) 367-378 (2006)mentioning

confidence: 99%

Current Transients from Passive Iron Surface during Micro-indentation

Fushimi¹,

Takase²,

Azumi³

et al. 2006

ECS Trans.

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Micro-indentation test of passive iron surface in pH 8.4 borate buffer solution was carried out to analyze current transients corresponding to the rupture and repair of passive film. During driving a conical diamond micro- indenter downward to the passive surface and driving upward from the surface, a couple of anodic current peaks were observed. The first current peak spiked during loading was responsible for partial exposure of iron substrate to the solution due to rupture of the passive film when the indenter tip deformed the substrate and penetrated. The second peak emerged during unloading when elastic deformation of the substrate recovered, which was ascribed to repair at the ruptured sites. The second peak current was larger than the first one. Both peaks were sensitively influenced by electrode potential or concentration of sulfate ions containing in solution. The model for a series of rupture and repair processes of the passive film by micro- indentation was proposed to discuss the current transients.

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Pitting Corrosion

Abstract: The sections in this article are Introduction Phenomenological Aspects of Pitting Critical Potentials and Polarization Curves Pitting and Cathodic Counterreactions Test Procedures and Ranking of Metals Potentiostatic Current–time Curves Pit Growth … Show more

Cited by 7 publications

References 49 publications

Microbial communities associated with wet flue gas desulfurization systems

Microbial communities associated with wet flue gas desulfurization systems

Effect of halide anions and temperature on initiation of pitting in Cr–Mn–N and Cr–Ni steels

Current Transients from Passive Iron Surface during Micro-indentation

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