• Title/Summary/Keyword: Corrosion Model

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Enhanced Classical Tafel Diagram Model for Corrosion of Steel in Chloride Contaminated Concrete and the Experimental Non-Linear Effect of Temperature

  • Hussain, Raja Rizwan
    • International Journal of Concrete Structures and Materials
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    • v.4 no.2
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    • pp.71-75
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    • 2010
  • The chloride ion attack on the passive iron oxide layer of reinforcement steel embedded in concrete under variable temperature environment is influenced by several parameters and some of them still need to be further investigated in more detail. Different school of thoughts exist between past researchers and the data is limited in the high temperature and high chloride concentration range which is necessary with regards to setting boundary conditions for enhancement of tafel diagram model presented in this research. The objective of this paper is to investigate the detrimental coupled effects of chloride and temperature on corrosion of reinforced concrete structures in the high range by incorporating classical Tafel diagram chloride induced corrosion model and laboratory controlled experimental non-linear effect of temperature on corrosion of rebar embedded in concrete.

Probabilistic time-dependent sensitivity analysis of HPC bridge deck exposed to chlorides

  • Ghosh, Pratanu;Konecny, Petr;Lehner, Petr;Tikalsky, Paul J.
    • Computers and Concrete
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    • v.19 no.3
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    • pp.305-313
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    • 2017
  • A robust finite element based reinforced concrete bridge deck corrosion initiation model is applied for time-dependent probabilistic sensitivity analysis. The model is focused on uncertainties in the governing parameters that include variation of high performance concrete (HPC) diffusion coefficients, concrete cover depth, surface chloride concentration, holidays in reinforcements, coatings and critical chloride threshold level in several steel reinforcements. The corrosion initiation risk is expressed in the form of probability over intended life span of the bridge deck. Conducted study shows the time-dependent sensitivity analysis to evaluate the significance of governing parameters on chloride ingress rate, various steel reinforcement protection and the corrosion initiation likelihood. Results from this probabilistic analysis provide better insight into the effect of input parameters variation on the estimate of the corrosion initiation risk for the design of concrete structures in harsh chloride environments.

Development of Chemical Decontamination Process of Stainless Steel for Reactor Coolant Pump(II) (원자로 냉각재 펌프용 스테인리스강에 대한 화학적 제염 공정 개발(II))

  • Kim, Seong-Jong;Kim, Jeong-Il;Kim, Ki-Joon
    • Journal of the Korean institute of surface engineering
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    • v.40 no.6
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    • pp.271-278
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    • 2007
  • In this study, applicable possibility in chemical decontamination for reactor coolant pump(RCP) was investigated for the various stainless steels. The stainless steel(STS) 304 showed the best electrochemical properties for corrosion current density and the lowest weight loss ratio in chemical decontamination process model 3-3 than other materials. The weightloss quantity in chemical decontamination process model 3-3 presents the lowest value compare to the other chemical decontamination process model 1, 2, 3-1 and 3-2. In the case of SEM observation, the pitting corrosion was generated in both STS 415 and STS 431 with the increasing numbers of cycle. The intergranular corrosion in STS 431 was sporadically observed. The sizes of their pitting corrosion were also increased with increasing cycle numbers.

Assessment of Soil Characteristics on External Corrosion of Water Pipes (토양특성이 상수도관의 외부부식에 미치는 영향 평가)

  • Bae, Chul-Ho;Kim, Ju-Hwan;Park, Sang-Young;Kim, Jeong-Hyun;Hong, Seong-Ho;Lee, Kyoung-Jae
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.5
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    • pp.737-745
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    • 2006
  • The goal of this study is to present an external pit corrosion rate($p_{ecr}$) model with considering both the age of pipe and the soil characteristics. The correlation of nonlinear exponential model among conventional empirical models was a little higher than other empirical models in the prediction of $p_{ecr}$ according to the age of pipe. However, there has been a limit to predict Peer with the model by using only a pipe age since installation as a variable. The soil analysis results from sixty nine samples showed that all of the samples were non corrosive in the assessment of ANSI/AWWA scoring system. The correlation of soil corrosion factors and $p_{ecr}$ was also low. The application result of linear and nonlinear regression models that soil characteristics only showed a low correlation with $p_{ecr}$ Proposed nonlinear regression model in this study, with considering both the age of pipe and the soil characteristics, showed a little higher correlation ($R^2=0.46$) than conventional model.

Effects of Mg on corrosion resistance of Al galvanically coupled to Fe (Fe와 galvanic couple된 알루미늄의 내식성에 미치는 마그네슘의 영향)

  • Hyun, Youngmin;Kim, Heesan
    • Corrosion Science and Technology
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    • v.12 no.1
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    • pp.40-49
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    • 2013
  • Effects of magnesium and pH on corrosion of aluminum galvanically coupled to iron have studied by using potentio- dynamic and static tests for polarization curves, Mott-Schottky test for analysis of semiconductor property, and GD-AES and XPS for film analysis. Pitting potential was sensitive to magnesium as an alloying element but not to pH, while passive current was sensitive to pH but not to magnesium. It was explained with, instead of point defect model (PDM), surface charge model describing that the ingression of chloride depends on the state of surface charge and passive film at film/solution interface is affected by pH. In addition, galvanic current of aluminum electrically coupled to iron was not affected by magnesium in pH 8.4, 0.2M citrate solution but was increased by magnesium at the solution of pH 9.1. The galvanic current at pH 9.1 increased with time at the initial stage and after the exposure of about 200 minute, decreased and stabilized. The behavior of the galvanic current was related with the concentration of magnesium at the surface. It agreed with the depletion of magnesium at the oxide surface by using glow discharge atomic emission spectroscopy (GD-AES). In addition, pitting potential of pure aluminum was reduced in neutral pH solution where chloride ion maybe are competitively adsorbed on pure aluminum. It was confirmed by the exponential decrease of pitting potential with log of [$Cl^-$] around 0.025 M of [$Cl^-$] and linear decrease of the pitting potential. From the above results, unlike magnesium, alloying elements with higher electron negativity, lowering isoelectric point (ISE), are recommended to be added to improve pitting corrosion resistance of aluminum and its alloys in neutral solutions as well as their galvanic corrosion resistance in weakly basic solutions.

Development of a Forecasting Model for Refinery Crude Column Overhead Corrosion Control (원유 증류 공정 탑 상부의 부식 예측 모델 개발)

  • Kim, Seung-Nam;Kim, Jung-Hwan;Moon, Il
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.35 no.2
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    • pp.143-148
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    • 2011
  • Corrosion at the top of a distillation column is a common problem in refineries and chemical plants. In particular, severe damage has been inflicted in refineries by corrosive materials such as hydrogen sulfide and chlorine. Therefore, the mechanism of the corrosion occurring at the top of a distillation column has been analyzed, and a model for forecasting the corrosion rate has been developed. Four major materials were selected for modeling: $H_2S$, $CO_2$, $H^+$ and $Cl^-$. These were selected by taking into consideration their effect on the corrosion rate. Studies on the transport phenomenon and reaction engineering for this model were carried out, and the reliability of the model was verified on the basis of the data measured at a real refinery.

Failure Probability of Corrosion Pipeline with Varying Boundary Condition

  • Lee, Ouk-Sub;Pyun, Jang-Sik
    • Journal of Mechanical Science and Technology
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    • v.16 no.7
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    • pp.889-895
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    • 2002
  • This paper presents the effect of external corrosion, material properties, operation condition and design thickness in pipeline on failure prediction using a failure probability model. The predicted failure assessment for the simulated corrosion defects discovered in corroded pipeline is compared with that determined by ANSI/ASME B31G code and a modified B31G method. The effects of environmental, operational, and random design variables such as defect depth, pipe diameter, defect length, fluid pressure, corrosion rate, material yield stress and pipe thickness on the failure probability are systematically studied using a failure probability model for the corrosion pipeline.

Buckling capacity of uniformly corroded steel members in terms of exposure time

  • Rahgozar, Reza;Sharifi, Yasser;Malekinejad, Mohsen
    • Steel and Composite Structures
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    • v.10 no.6
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    • pp.475-487
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    • 2010
  • Most of steel structures in various industries are subjected to corrosion due to environmental exposure. Corrosion damage is a serious problem for these structures which may reduce their carrying capacity. These aging structures require maintenance and in many cases, replacement. The goal of this research is to consider the effects of corrosion by developing a model that estimates corrosion loss as a function of exposure time. The model is formulated based on average measured thickness data collected from three severely corroded I-beams (nearly 30 years old). Since corrosion is a time-dependent parameter. Analyses were performed to calculate the lateral buckling capacity of steel beam in terms of exposure time. Minimum curves have been developed for assessment of the remaining lateral buckling capacity of ordinary I-beams based on the loss of thicknesses in terms of exposure time. These minimum curves can be used by practicing engineers for better estimates on the service life of corrosion damaged steel beams.

Corrosion model for Zircaloy-4 Cladding in PWR

  • Lee, Byung-Ho;Yoo, Yeon-Jong;Kook, Yang-Hyun;Sohn, Dong-Seong
    • Proceedings of the Korean Nuclear Society Conference
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    • 1999.05a
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    • pp.279-279
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    • 1999
  • To improve the corrosion model of the fuel performance analysis code COSMOS, a model was developed considering thermohydraulic phenomena and the effect of water chemistry and low Sn in the alloy composition on the corrosion behavior. It is assumed that the lithium enhancement factor influences the corrosion behavior only if the subcooled void is present in the coolant. The developed model was verified with the database obtained from Grohnde and Ringhals 3 reactors. Comparison of predicted oxide thickness with measured data showed the applicability of COSMOS code to analyze the cladding oxidation. In the future, the effect of the hydride in the cladding and the precipitate changes due to irradiation should be included.cluded.

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Fatigue life evolution of steel wire considering corrosion-fatigue coupling effect: Analytical model and application

  • Yang Ding;Xiao-Wei Ye;Hong Zhang;Xue-Song Zhang
    • Steel and Composite Structures
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    • v.50 no.3
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    • pp.363-374
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    • 2024
  • The fatigue life of steel wire is affected not only by fatigue load, but also by corrosion environment in service period. Specially, the corrosion pit will lead to stress concentration on the surface of steel wire inducing the formation of fatigue cracks, and the fatigue cracks will accelerate the corrosion process. Therefore, the corrosion fatigue of steel wire is a coupling effect. In this study, the corrosion-fatigue coupling life curve is derived with considering corrosion-fatigue pitting stage, corrosion-fatigue short crack stage and corrosion-fatigue long crack stage. In addition, the stress concentration factors of different corrosion pits are calculated by COMSOL software. Furthermore, the effect of corrosion environment factors, that is, corrosion rate, corrosion pit morphology, frequency and action factor of fatigue load, on fatigue life of steel wire is analyzed. And then, the corrosion-fatigue coupling life curve is compared with the fatigue life curve and fatigue life curve with pre-corrosion. The result showed that the anti-fatigue performance of the steel wire with considering corrosion-fatigue coupling is 68.08% and 41.79% lower than fatigue life curve and fatigue life curve with pre-corrosion. Therefore, the corrosion-fatigue coupling effect should be considered in the design of steel wire.