Prediction and Measurement of Pitting Damage Functions for Condensing Heat Exchangers

Macdonald, D. D.; Liu, C.; Urquidi‐Macdonald, Mirna; Stickford, G. H.; Hindin, B.; Agrawal, A. K.; Krist, K.

doi:10.5006/1.3293466

Cited by 20 publications

(5 citation statements)

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“…The methods outlined above have now been used to predict failure times for a number of speci®c systems, including stainless steel condensing heat exchangers [65], low pressure steam turbines (due to pitting/stress corrosion cracking) [64], and steel ball bearings in contaminated oil [66]. In the ®rst case, the failure of condensing heat exchanges, pitting occurs under a thin condensate ®lm that forms on the Fig.…”

Section: Repassivationmentioning

confidence: 99%

“…The calculated failure times, for a given duty cycle (i.e. sequence of on/off periods for the burner, and hence for cyclical variations in the gas composition), were compared with Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 7/27/15 6:41 AM those measured in instrumented heat exchangers by the Battelle Columbus Laboratories in a double-blind manner [65]. The results are plotted in Fig.…”

Section: Repassivationmentioning

confidence: 99%

“…¯ue side of the stainless steel (Type 304L) heat exchanger [65]. Because of the aggressiveness of this environment, delayed pit repassivation was judged to be unimportant, but the damage was considered to evolve in a progressive nature.…”

Section: Repassivationmentioning

confidence: 99%

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Passivity–the key to our metals-based civilization

Macdonald¹

1999

Pure and Applied Chemistry

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678

671

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Humankind has been able to develop a metals-based civilization primarily because the reactive metals (Fe, Ni, Cr, Al, Ti, Zr, . . .) exhibit extraordinary kinetic stabilities in oxidizing environments. From the time of Schonbein and Faraday (1830s), the reason for this stability has been attributed to the existence of a thin reaction product ®lm on the metal (or alloy) surface. This ®lm effectively isolates the metal from the corrosive environment. However, attempts to elucidate the mechanisms of the formation of passive oxide ®lms, which generally comprise bilayer structures consisting of a defective oxide that grows directly into the metal and an outer, precipitated hydroxide (or oxyhydroxide on even oxide) layer, have yielded only a rudimentary understanding of the chemistry and physics of the growth and breakdown processes. In this paper, selected aspects of passivity and passivity breakdown are reviewed, with emphasis on the physical models that have been proposed to account for the experimental observations. One such model, the Point Defect Model, is shown to account for most, if not all, experimental observations, and to provide a robust basis for predicting the occurrence of passivity breakdown in any given system. By combining the Point Defect Model with deterministic models for pit growth and crack growth, it is now possible to predict the evolution of localized corrosion damage in a wide range of systems.

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Section: Repassivationmentioning

confidence: 99%

Section: Repassivationmentioning

confidence: 99%

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Passivity–the key to our metals-based civilization

Macdonald¹

1999

Pure and Applied Chemistry

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678

671

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“…Condensate liquids produced by natural gas condensing furnaces during operation are known to be acidic and corrosive to metallic alloys [17][18][19][20]. Type-1 aluminized lowcarbon steel from a commercial natural gas condensing furnace was obtained for corrosion investigation.…”

Section: Corrosion Testing and Icp-oesmentioning

confidence: 99%

Characterization and Electrochemical Analysis of Acidic Condensate-Induced Corrosion on Aluminized Coating on Steel in Residential Heaters

Sulejmanovic,

Jun,

Gao

et al. 2023

Coatings

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Condensing furnace residential heaters are starting to replace outdated and less efficient non-condensing units in homes across the US. However, the burning of natural gas in these new units produces acidic gases, which can form acid droplets (H2SO4, HNO3, H2CO3, etc.) that are corrosive to low-grade heat exchanger metallic materials. Type-1 aluminized steel has been used in industrial applications, such as marine, heating, and automobile parts, due to its resistance to oxidation at elevated temperature. Many components of the condensing furnaces, including heat exchangers, are made from type-1 aluminized steel. We investigated the interaction of type-1 aluminized steel substrates with two acidic condensate liquids by 500 h corrosion exposures as well as short-term electrochemical impedance measurements. SEM plan and cross-sectional view images revealed damage to the Al-Si rich layer and exposure of the steel substrate. The non-uniform damage in the Al-Si rich layer was likely attributed to a pitting corrosion mechanism and induced by high acidity of the condensate liquid. Electrochemical impedance measurements in an acidic condensate revealed lower corrosion resistance of the aluminized steel surface with a weld line, identifying welded sections as preferential corrosion initiation sites.

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“…The first term of Equation (1) is based on the point defect model (PDM) [6][7][8][9][10] which describes passive film break. The second is a mechanical term.…”

Section: Master Equation Of Igscc Initiationmentioning

confidence: 99%

Intergranular stress corrosion cracking initiation model of austenite stainless steels used in BWRs for optimized water chemistry control

Wada

Watanabe

Ishida

et al. 2013

Journal of Nuclear Science and Technology

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A calculation model on intergranular stress corrosion cracking (IGSCC) initiation time of materials used in boiling water reactors (BWRs) has been developed to evaluate effectiveness of water chemistry control for mitigation of the IGSCC. The model was composed of four terms which determine passive film break time:(1) a chemical term based on electrochemical corrosion potential (ECP) and impurity concentration; (2) a mechanical term based on strain rate; (3) a material term based on sensitization; and (4) an irradiation term based on acceleration of corrosion by γ -rays and neutron irradiation. The contribution of the chemical term in the passive film break was calculated based on a deterministic local corrosion model. Then, the local corrosion model was modified by adding mechanical acceleration of the film rupture to treat the IGSCC phenomenon. The model could reproduce the behavioral tendency seen in the slow strain rate tensile test on high carbon contents with sensitization heat treatment (for example, 620• C × 24 h). Under BWR operating conditions, IGSCC initiation time could be extended by a factor of 5 by lowering the electric conductivity from 1.0 to 0.06 μS/cm. If the ECP was reduced below the critical potential by a mitigation method, the IGSCC initiation time was predicted to become sufficiently long for pipings and components.

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Prediction and Measurement of Pitting Damage Functions for Condensing Heat Exchangers

Cited by 20 publications

References 0 publications

Passivity–the key to our metals-based civilization

Passivity–the key to our metals-based civilization

Characterization and Electrochemical Analysis of Acidic Condensate-Induced Corrosion on Aluminized Coating on Steel in Residential Heaters

Intergranular stress corrosion cracking initiation model of austenite stainless steels used in BWRs for optimized water chemistry control

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