A Neural Based Fuzzy Logic Model to Determine Corrosion Rate for Carbon Steel Subject to Corrosion under Insulation

2015 ◽  
Vol 789-790 ◽  
pp. 526-530 ◽  
Author(s):  
Muhammad Mohsin Khan ◽  
Ainul Akmar Mokhtar ◽  
Hilmi Hussin
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Degradation Mechanism ◽  
Fuzzy Model ◽  
American Petroleum Institute ◽  
Carbon Steels ◽  
Corrosion Monitoring ◽  
Absolute Deviation ◽  
External Corrosion ◽  
Corrosion Under Insulation

One of the most common external corrosion failures in petroleum and power industry is due to corrosion under insulation (CUI). The difficulty in corrosion monitoring has contributed to the scarcity of corrosion rate data to be used in Risk-Based Inspection (RBI) analysis for degradation mechanism due to CUI. Limited data for CUI presented in American Petroleum Institute standard, (API 581) reflected some uncertainty for both stainless steels and carbon steels which limits the use of the data for quantitative RBI analysis. The objective of this paper is to present an adaptive neural based fuzzy model to estimate CUI corrosion rate of carbon steel based on the API data. The simulation reveals that the model successfully predict the corrosion rates against the values given by API 581 with a mean absolute deviation ( MAD ) value of 0.0005, within that the model is also providing its outcomes for those values even for which API 581 has not given its results. The results from this model would provide the engineers to do necessary inferences in a more quantitative approach.

scholarly journals The effect of volatile organic acids and CO2 on the corrosion rate of carbon steel from a Top-of-Line-Corrosion (TLC) perspective

2021 ◽  
Vol 1201 (1) ◽  
pp. 012079
Author(s):  
S B Gjertsen ◽  
A Palencsar ◽  
M Seiersten ◽  
T H Hemmingsen
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Organic Acid ◽  
Carbonic Acid ◽  
Acid Corrosion ◽  
Iron Concentration ◽  
Critical Factor ◽  
Steel Corrosion ◽  
Carbon Steels ◽  
Corrosion Rates

Abstract Models for predicting top-of-line corrosion (TLC) rates on carbon steels are important tools for cost-effectively designing and operating natural gas transportation pipelines. The work presented in this paper is aimed to investigate how the corrosion rates on carbon steel is affected by acids typically present in the transported pipeline fluids. This investigation may contribute to the development of improved models. In a series of experiments, the corrosion rate differences for pure CO2 (carbonic acid) corrosion and pure organic acid corrosion (acetic acid and formic acid) on X65 carbon steel were investigated at starting pH values; 4.5, 5.3, or 6.3. The experiments were conducted in deaerated low-salinity aqueous solutions at atmospheric pressure and temperature of 65 °C. The corrosion rates were evaluated from linear polarization resistance data as well as mass loss and released iron concentration. A correlation between lower pH values and increased corrosion rates was found for the organic acid experiments. However, the pH was not the most critical factor for the rates of carbon steel corrosion in these experiments. The experimental results showed that the type of acid species involved and the concentration of the undissociated acid in the solution influenced the corrosion rates considerably.

scholarly journals Corrosion Behavior of Materials Al5083 Alloy, 316L Stainless Steel and A681 Carbon Steel in Seawater

2021 ◽  
Vol 44 (2) ◽  
pp. 39-46
Author(s):  
Gina Genoveva ISTRATE ◽  
Alina Crina MUREȘAN
Keyword(s):  
Weight Loss ◽  
Stainless Steel ◽  
Carbon Steel ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Aluminium Alloys ◽  
Saturated Calomel Electrode ◽  
Open Circuit ◽  
Carbon Steels ◽  
Test Technique

In this paper the corrosion behavior of different materials has been evaluated based on exposure in seawater. The laboratory immersion test technique has been applied to evaluate the effect of seawater on the corrosion behavior of different materials. In three sets of experiments, carbon steels (A681 Type O7), austenitic stainless steels (316L) and aluminium alloys (Al5083) were utilized. The specimens were fixed fully submerged in seawater. The corrosion process was evaluated using weight loss method, open-circuit potential measurements (OCP) and polarization techniques. To determine gravimetric index and the rate of penetration, samples were immersed in corrosive environment for 89 days and weighed periodically. The electrochemical experiments were conducted with a Potentiostat/Galvanostat (PGP 201) analyzer. It was connected to a PC. The Voltamaster software was used for electrochemical data analysis. A three-electrode cell composed of a specimen as a working electrode, Pt as counter electrode, and saturated calomel electrode (SCE) (Hg (l)/ Hg2Cl2 (s)) as a reference electrode were used for the tests. The weight loss tests revealed the lowest corrosion rate values for stainless steel and aluminium alloys, indicating a beneficial use for these materials in marine environments. The potentiodynamic method shows that the lowest corrosion rate in seawater (2.8 μm /year) was obtained for the Al5083 alloy, and the highest value of the corrosion rate (41.67 μm/year) for A681 carbon steel.

Corrosion behaviors of steels under supercritical CO2 conditions

2015 ◽  
Vol 33 (3-4) ◽  
pp. 151-174 ◽  
Author(s):  
Liang Wei ◽  
Yucheng Zhang ◽  
Xiaolu Pang ◽  
Kewei Gao
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Stainless Steels ◽  
Steel Corrosion ◽  
Carbon Steels ◽  
Corrosion Mechanism ◽  
Electrochemical Behaviors ◽  
Structure Morphology ◽  
Corrosion Behaviors ◽  
Corrosion Scales

AbstractCarbon dioxide (CO2) corrosion at low partial pressure has been widely recognized, but research on supercritical CO2 (SC CO2) corrosion is very limited. By far, investigations on steel corrosion under SC CO2 conditions have mainly focused on the corrosion rate, structure, morphology, and composition of the corrosion scales as well as the electrochemical behaviors. It was found in aqueous SC CO2 environment, that the corrosion rate of carbon steel was very high, and even stainless steels (13Cr and high-alloy CrNi steels) were subjected to some corrosion. Inhibitor could reduce the corrosion rate of carbon steels and stainless steels, but none of the tested inhibitors could reduce the corrosion rate of carbon steel to an acceptable value. Impurities such as O2, SO2, and NO2 and their mixtures in SC CO2 increased the corrosion rate of carbon steel. However, the existing studies so far were very limited on the corrosion mechanism of steels in SC CO2 conditions. Thus, this paper first reviews the finding on the corrosion behaviors of steels under SC CO2 conditions, points out the shortcomings in the present investigations and finally looks forward to the research prospects on SC CO2 corrosion.

Corrosion of Carbon-Steel Containers for Heat-Generating Nuclear Waste in Brine Environments Relevant for A Rock-Salt Repository

1991 ◽  
Vol 257 ◽  
Author(s):  
E. Smailos ◽  
W. Schwarzkopf ◽  
B. Kienzler ◽  
R. KÖster
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Nuclear Waste ◽  
Rock Salt ◽  
Corrosion Behaviour ◽  
Carbon Steels ◽  
General Corrosion ◽  
Fine Grained ◽  
Corrosion Studies ◽  
Salt Brine

ABSTRACTIn previous corrosion studies, carbon steels, especially the fine-grained steel TStE355, were identified as promising materials for heat-generating nuclear waste containers acting as a barrier in a rock-salt repository. In the present study detailed investigations have been performed on fine-grained steel to determine the influence of important parameters on its corrosion behaviour in disposal-relevant salt brines. These parameters are: brine composition (Mg Cl2-rich and NaCI-rich brines), temperature (90°C, 170°C), and salt impurities, such as H2S concentrations of 25 mg/I-200 mg/I salt brine.Under the conditions of the tests used here, carbon steel was subjected to general corrosion. Pitting and crevice corrosion or stress-corrosion cracking were not observed. The increase in temperature from 90°C to 170°C strongly enhanced the corrosion rate of the steel. In the MgCl2-rich brines, considerably higher rates (37-70 μm/a at 90°C, 200-300 °m/a at 170°C) were observed than in the NaCI-rich brine (5 μm/a at 90°C, 46 μm/a at 170°C). H2S concentrations in the MgCl2-rich Qbrine of up to 200 mg/l did not influence significantly the corrosion rate of the steel. The corrosion rates determined imply corrosion allowances that are technically acceptable for thick-walled containers. In view of these results, fine-grained steel continues to be considered as a promising material for long-lived HLW containers.

On the Probabilistic Distribution of External Pitting Corrosion Rate in Buried Pipelines

2008 ◽  
Author(s):  
F. Caleyo ◽  
J. C. Vela´zquez ◽  
J. M. Hallen ◽  
J. E. Araujo ◽  
E. Perez-Baruch
Keyword(s):  
Corrosion Rate ◽  
Power Law ◽  
Pitting Corrosion ◽  
Oil And Gas ◽  
Degradation Mechanism ◽  
Clay Loam ◽  
Buried Pipelines ◽  
Southern Mexico ◽  
External Corrosion ◽  
Corrosion Pits

External pitting corrosion constitutes the degradation mechanism responsible for about 66% of the incidents reported in the last decade for oil and gas pipelines in Mexico. Thus, major efforts are underway to improve the characterization and modeling of pitting corrosion of buried pipelines. Special attention is devoted to estimate the average corrosion rate and corrosion rate variance because they are the key parameters in the estimation of the trend in pipeline reliability. This work presents the results of field and simulation studies in which soil and pipe data were gathered together with the maximum depth of external corrosion pits found at more than 250 excavation sites across southern Mexico. The distributions of parameters such as chloride, bicarbonate and sulfate levels, resistivity, pH, pipe/soil potential, humidity, redox potential, soil texture and coating type have been used to predict the distribution of pitting corrosion rate of pipelines in contact with clay, clay-loam and sandy-clay-loam soils. The time dependence of the pitting corrosion rate was fitted to a power law through a multivariate regression analysis with the maximum pit depth as the dependent variable and the pipeline age and the soil and coating properties as the independent variables. Monte Carlo simulations were conducted in which random values drawn from the distributions fitted to the field data were used to evaluate the power law model proposed for the corrosion rate. For each soil type, the distribution that best fitted the corrosion rate data was found. The results of this study will provide reliability analysts with a more accurate description of the growth rate of external corrosion pits. It is expected that this information will positively impact on integrity management plans addressing the threat posed by this damage mechanism.

scholarly journals Internal corrosion of carbon steel piping in hot aquifers service

2011 ◽  
Vol 65 (3) ◽  
pp. 303-311
Author(s):  
Milos Simicic ◽  
Dragan Govedarica
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Corrosion Inhibitor ◽  
Elevated Temperatures ◽  
Corrosion Monitoring ◽  
Internal Corrosion ◽  
Protective Films ◽  
Water Pipelines ◽  
Corrosion Modelling ◽  
Carbonate Film

Internal corrosion of carbon steel pipelines is a major problem encountered in water service. In terms of prediction of the remaining lifetime for water pipelines based on the corrosion allowance, the three main approaches are corrosion modelling, corrosion inhibitor availability, and corrosion monitoring. In this study we used two theoretical corrosion models, CASSANDRA and NORSOK M-506 of quite different origin in order to predict uniform corrosivity of hot aquifers in eight different pipelines. Because of the varying calculation criteria for the different models, these can give very different corrosion rate predictions for the same data input. This is especially true under conditions where the formation of protective films may occur, such as at elevated temperatures. The evaluation of models was conducted by comparison using weight-loss coupons and three corrosion inhibitors were obtained from commercial suppliers. The tests were performed during the 60-day period. Even though inhibitors? efficiencies of 98% had been achieved in laboratory testing, inhibitors? availabilities of 85% have been used due to logistics problems and other issues. The results, given in mmpy, i.e. millimeter per year, are very consistent with NORSOK M-506 prediction. This is presumably because the model considers the effect of the formation of a passive iron carbonate film at temperatures above 80 ?C and significant reduction in corrosion rate. Corrosion inhibitor A showed a better performance than inhibitors B and C in all cases but the target corrosion rates of less than 0.1 mmpy were achieved for all inhibitors. The chemical type of corrosion inhibitor A is based on quaternary amines mixed with methanol, isopropyl alcohol, xylene and ethylbenzene. Based on the obtained results the carbon steel lifetime of 30 years, provided proper inhibitors are present and 3mm corrosion allowance, can be achieved for hot aquifers service with presented water compositions.

scholarly journals Long-term corrosion monitoring of carbon steels and environmental correlation analysis via the random forest method

2022 ◽  
Vol 6 (1) ◽  
Author(s):  
Qing Li ◽  
Xiaojian Xia ◽  
Zibo Pei ◽  
Xuequn Cheng ◽  
Dawei Zhang ◽  
...  
Keyword(s):  
Random Forest ◽  
Corrosion Rate ◽  
Atmospheric Corrosion ◽  
Chloride Concentration ◽  
Carbon Steels ◽  
Sensor Data ◽  
Corrosion Monitoring ◽  
Atmospheric Conditions ◽  
Data Points

AbstractIn this work, the atmospheric corrosion of carbon steels was monitored at six different sites (and hence, atmospheric conditions) using Fe/Cu-type atmospheric corrosion monitoring technology over a period of 12 months. After analyzing over 3 million data points, the sensor data were interpretable as the instantaneous corrosion rate, and the atmospheric “corrosivity” for each exposure environment showed highly dynamic changes from the C1 to CX level (according to the ISO 9223 standard). A random forest model was developed to predict the corrosion rate and investigate the impacts of ten “corrosive factors” in dynamic atmospheres. The results reveal rust layer, wind speed, rainfall rate, RH, and chloride concentration, played a significant role in the corrosion process.

The electrochemical behavior of corrosion and passivation for Q235 carbon steel in acidic phosphate buffer solutions without and with NO2−

2020 ◽  
Vol 67 (5) ◽  
pp. 473-481
Author(s):  
Xiaochen Hu ◽  
Pei Zhang ◽  
Yong Zhou ◽  
Fuan Yan
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Phosphate Buffer ◽  
Surface Passivation ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Carbon Steels ◽  
Content Type ◽  
Anodic Passivation ◽  
Q235 Carbon Steel

Purpose The purpose of this paper is to reveal the mechanism of nitrite (NO2−) for the surface passivation of carbon steels in acidic environments through investigating the influences of 0.01 mol/L NaNO2 addition on the corrosion and passivation behaviors of Q235 carbon steel in acidic phosphate buffer (APB) solutions (pH 2 to 6). Design/methodology/approach The electrochemical techniques including open circle potential evolution, potentiodynamic polarization, electrochemical impedance spectroscopy and cyclic voltammetry were applied. Findings In APB solutions without NO2−, the Q235 steel presented the electrochemical behaviors of activation (A), activation-passivation-transpassivation and self-passivation-transpassivation at pH 2 to 4, pH 5 and pH 6, respectively; the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6. Originality/value In APB solutions without NO2−, the corrosion rate decreased with the up of pH value, and the surface passivation occurred in the pH 5 and pH 6 solutions only: the anodic passivation at pH 5 and the spontaneous passivation at pH 6. With the addition of 0.01 mol/L NaNO2, into APB solutions, the variation of corrosion rate showed the same rule, but the surface passivation occurred over the whole acidic pH range, including the anodic passivation at pH 2 to 4 and the spontaneous passivation at pH 5 to 6.

Effect of Immersion and Green Inhibitor to Corrosion Rate of Carbon Steel

2015 ◽  
Vol 1087 ◽  
pp. 276-281
Author(s):  
A. Ismail ◽  
Mohd Fuzaimie Ahmad Fuad
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Corrosion Product ◽  
Protective Layer ◽  
Immersion Test ◽  
Chemical Substance ◽  
Carbon Steels ◽  
Banana Peel ◽  
Corrosion Attack ◽  
Green Inhibitor

Corrosion is the reaction between the material and the environment that cause degradation of the material. Corrosion reduces the essential properties of materials such as strength, appearance, toughness and life expectancy. Carbon steels are composed of a mixture of metallic iron and carbon and being used extensively in every sector due to good mechanical properties and good cost. However, carbon steel are every susceptible to corrosion attack especially in corrosive environment. The use of inhibitors is one of the best options to protect against corrosion on metals and alloys especially in a closed system. Inhibitor is a chemical substance which can reduce corrosion attack when added into electrolyte. The organic inhibitor used in this study was from banana peel (scientific name Musa sapieutum) to extract tannin-a compound which can provide protective layer on metal [1-3]. The results elucidate that banana peel can be used as green inhibitor on canbon steel, however, the effect only can be seen when added with 10% and more. The immersion test was done to evaluate the effect of corrosion product to corrosion rate. The results explained that corrosion rate fluctuated during immersion period due to developed and dissolved of soluble product into electrolyte. The research provide a set of data elucidate that corrosion product developed on carbon steel cannot provide corrosion protection on carbon steel, however, using green inhibitor in high concentrations which is purely not harmful to environment could prevent corrosion attack on carbon steel.

Corrosion of high strength carbon steels in siderite supersaturated water at near neutral pH

CORROSION ◽  
10.5006/3514 ◽  
2021 ◽  
Author(s):  
Tatiane Campos ◽  
Marion Seiersten ◽  
Simona Palencsár ◽  
Arne Dugstad ◽  
JOSE ANTONIO PONCIANO GOMES
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Steel Surface ◽  
High Strength ◽  
Carbon Steels ◽  
Ion Concentration ◽  
Liquid Volume ◽  
Ferrous Ions ◽  
Bicarbonate Concentration ◽  
Neutral Ph

When carbon steel corrodes in anaerobic carbonated water, and the steel surface area to liquid volume is high, the concentration of ferrous and bicarbonate ions increases rapidly even though the corrosion rate is low. Such solutions with high bicarbonate concentration and a near neutral pH, are believed to induce stress corrosion cracking (SCC) of high strength carbon steels. This work was conducted to investigate the solid precipitation in siderite supersaturated solutions. It was also an objective to measure the corrosion rate of high strength carbon steel in solutions with high bicarbonate concentration at pH close to neutral. Pre-loading the solutions with ferrous ions and bicarbonate made it possible to measure de-supersaturation and corrosion rate as function of time. The initial siderite supersaturation was more than 1000 in the de-supersaturation experiments. Despite this, the nucleation and growth of siderite was so slow, that the solutions remained supersaturated for 100 to 500 h at 10 to 25 °C. The ferrous ion concentration decreased from 1200 to 100 mg.kg-1 in less than 24 h at 40 °C, but did not reach equilibrium within 250 h. The precipitate was siderite at 5 to 25 °C. At 40 °C, the solid was a mixture of siderite and chuckanovite in low salinity water and siderite with dissolved Ca2+ in artificial seawater. The corrosion rate of carbon steel at pH 6.7 to 7.2 at 25 °C decreased to less than 0.01 mm.y-1 in 5 h. Siderite precipitated and grew to a thin protective layer at the steel surface. Even though the solutions were highly supersaturated with respect to siderite throughout the experiments, the carbonate layer at the steel surface did not grow to more 5 µm thickness during 250 to 400 h. The investigated steels were armor wires for flexible pipes. They have an oxide layer at the surface which is an inherent result of the manufacturing process. The presence of these oxides did not impede the formation of protective siderite layer.

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