Corrosion Index Research Articles

Developing an innovative corrosion and scaling index for industrial cooling water using artificial intelligence

The present study developed an intelligent model to predict the corrosion and scaling potential (CSP) of industrial cooling water circuits using artificial intelligence (AI) techniques. AI techniques have attracted a lot of attention due to the high accuracy and speed of calculations, as well as possible analysis of large datasets. The study analyzed nine years of data on cooling water quality parameters, including pH, alkalinity, hardness, dissolved solids, chloride, turbidity, suspended solids, and iron, from electric arc furnaces at the Khuzestan Steel Company. Multiple linear regression (MLR), multiple nonlinear regression (MNLR), and multi-layer perceptron neural network (ANN-MLP) models were applied to predict CSP. The ANN-MLP model achieved the best performance with an R2 of 0.75, Mean Absolute Error of 0.34, and Mean Squared Error of 0.35, demonstrating that neural networks can effectively predict CSP in industrial cooling water. The results also showed that total hardness and chloride have the greatest impact on CSP in the circulating water circuits.

Evaluating the Effects of Polyphosphate Cartridge at Point-of-Entry on Scaling and Corrosion Indices of Household Water

Scaling and corrosion are significant issues in water distribution systems that can lead to economic, aesthetic, and health concerns. This study aimed to investigate the effects of a point-of-entry (POE) polyphosphate cartridge on scaling and corrosion indices (Langelier Saturation Index [LSI], Ryznar Stability Index [RSI], Puckorius Scaling Index [PSI] and Aggressive Index [AI]), as well as the quality of water treated with household water treatment systems. In this study, a POE polyphosphate cartridge was directly connected to municipal water to adjust water stability and prevent scaling and corrosion. Parameters were tested in water samples before and after filtration with the POE polyphosphate cartridge. Spearman’s correlation analysis was conducted to determine any monotonic relationship between the variables using SPSS. It was observed that water exhibited scaling properties at flow rates of 0.180, 0.252, and 0.522 L/min based on the LSI, while in other cases, it showed corrosion properties. Additionally, the results of the Spearman analysis indicated a strong positive correlation (r=0.74) between RSI and PSI and a strong negative correlation (r=-0.64) between LSI and RSI in the outlet water from the POE polyphosphate cartridge. The results indicated that more precise control of key quality parameters for scaling and corrosion of water is essential. Significant adjustments must be implemented to prevent corrosion of facilities and valves when utilizing a POE polyphosphate cartridge in household water systems. Moreover, due to the fluctuations in household water consumption, the use of inline POE polyphosphate cartridges may not ensure water stability in the household water supply system.

Graphical, statistical and index-based techniques integrated for identifying the hydrochemical fingerprints and groundwater quality of In Salah, Algerian Sahara.

Groundwater, a predominant reservoir of freshwater, plays a critical role in providing a sustainable potable water and water for agricultural and industry uses in the In Salah desert region of Algeria. This research collected 82 underground water samples from Albian aquifers to assess water quality and identify hydrogeochemical processes influencing mineralization. To achieve this objective, various methods were employed to evaluate water quality based on its intended uses. The drinking water quality index utilized revealed the water potability status, while the indicators of irrigation potability were employed to evaluate its quality for agricultural purposes. Additionally, an assessment of groundwater susceptibility to corrosion and scaling in an industrial context was conducted using several indices, e.g., Langelier index, Larson-Skold index, Ryznar index, chloride-sulfate mass ratio, Puckorius index, aggressiveness index, and the Revelle index. The findings of this study revealed thatthe groundwater quality for consumption fell into four categories: good (2.44%), fair (29.27%), poor (65.85%), and non-potable (2.44%). Concerning agricultural irrigation, the indexical results indicated that 15.85% of the waters exhibited adequate quality, while 84.15% were questionable for irrigation. Calculations based on various corrosion and scaling evaluation indices showed that most wells were prone to corrosion, with a tendency for calcium bicarbonate deposit formation. Furthermore, the hydrochemical study identified three water types: Na-Cl (53.66%), Ca-Mg-Cl (37.80%), and Ca-Cl (8.54%) waters. Analyses of correlation matrices, R-type clustering, factor loadings, Gibbs diagrams, scatterplots, and chloro-alkaline indices highlighted that the chemistry of the Albian groundwater is fundamentally impacted by a number of processes such as silicate weathering, evaporite dissolution, ionic exchange, and anthropogenic inputs, that played impactful role in the aquifer's water chemistry.

A novel and effective approach to improve the oxidation resistance and slag corrosion resistance of Al2O3–SiC–C castables

The present study aims to clarify the role of ball pitch in Al2O3–SiC–C (ASC) refractory castables and investigate the influence of low temperature treatment on the composition, microstructural evolution, and properties of ASC refractory castables. By utilizing the expansion properties of ball pitch during heating, the castables undergo a low temperature treatment to induce the flow and expansion of ball pitch within the castables. This, in turn, fills the surrounding pores and enhances the physical properties of the castables. The results of this study demonstrate that low-temperature heat treatment of the castables at temperatures at 350 °C significantly improves the hot modulus of rupture, oxidation resistance, and slag resistance after sintering. This improvement is attributed to the optimized microstructure. In comparison to the corresponding samples without low temperature treatment, the high temperature modulus of rupture (HMOR) of the calcined castables treated at 350 °C increases by 33.3%. Additionally, the oxidation index and slag corrosion index after sintering at 1500 °C decrease by 39.6% and 87.31% respectively for the samples low temperature treated at 350 °C, as compared to the samples low temperature treated at 110 °C. This study provides a fresh perspective on the production of ASC castables with exceptional high temperature performance.

Effect of pretreated Al-Si alloy powder on the microstructure and properties of Al2O3-SiC-C castables for iron runner

In ferrotitanium slag-based Al2O3-SiC-C castables, owing to the presence of more impurities in the ferrotitanium slag, the liquid content at high temperatures is extremely high, which reduces the performance of the material. In this study, the Al-Si alloy powder was hydrated, and then pretreated Al-Si alloy powder (PASAP) was used to replace Si powder and micro-silica to reduce the content of liquid in the ferrotitanium slag-based Al2O3-SiC-C castables. Compared with the sample without PASAP, the sample with 5 wt% PASAP formed numerous whiskers in situ, and the hot modulus of rupture increased by 167%. Moreover, the decrease in the liquid content of the material and the dissolution of the molten slag by Al2O3 led to an increase in the slag viscosity. The slag corrosion index of the sample with 5 wt% PASAP is decreased by 67%.

Liquid-phase shear exfoliation combined with hydrothermal processing for the preparation of graphene nanosheet/AlOOH nanofiber composite powder to enhance high-temperature performance of MgO-carbon castable

Flake graphite (FG) poses challenges for incorporation into castables due to its hydrophobic nature. In this paper, a strategy combining liquid-phase shear exfoliation (LPSE) with hydrothermal processing was proposed to produce hydrophilic graphene nanosheet/AlOOH nanofiber (GN/ANF) composite powders to address this issue. Under optimal shear exfoliation conditions, the yield of graphene nanosheets (GNs) reached up to 57%. Following a straightforward hydrothermal treatment, the water contact angle of as-prepared GN/ANF composite powders decreased to 53.1°, compared to 103.6° of the original FG. Benefiting from the hydrophilic properties of the composite powders and the homogeneous dispersion of GNs in MgO castables, the sample containing 0.5 wt% GNs exhibited better high-temperature performance than its counterparts. Relative to the control specimen, the slag corrosion index of the sample containing 0.5 wt% GNs decreased from 0.60 to 0.13, while the thermal shock resistance increased by approximately 2.8 times.

Detection and localization of corrosion using the combination information of multiple Lamb wave modes

Themulti-modeanddispersionnature of Lamb waves means that a variety of modes with individual mode structures and distinct dispersion behaviors would propagate in the structures simultaneously. The existence of a corrosion would result in thickness reduction, which means the frequency-thickness product under a specific excitation would also decrease. Due to dispersion diversity, the interaction of each individual Lamb mode at the corrosion may be distinct, i.e., the velocity varies in different extent and even in opposite trends. In this paper, the combination of multiple modes, rather than a single sensitive mode, is used for structure diagnosis. Specifically, two Lamb modes both sensitive to corrosion but with opposite variation trends are taken and the corrosion index is defined on the ratio of their time-of-flight, so as to enhance the sensitivity to corrosion and eliminate the influence of difference path lengths in the sensor network. On this basis, a probabilistic reconstruction algorithm is introduced for corrosion detection and localization. Since the two modes are extracted from the same wideband Lamb wave response, the proposed method is baseline-free. The influence of mode conversion on the effectiveness of the proposed method is discussed. Ultimately, the performance of the proposed method is demonstrated by an experimental example. The results show that the defect could be correctly identified and accurately localized.

Corrosion mechanism of novel MgO–Al3BC3 refractories in contact with converter slag

The corrosion mechanism of novel MgO–Al3BC3 refractories in contact with converter slag was investigated. Results demonstrated that refractories with an optimized Al3BC3–Al composition exhibited significantly reduced corrosion index compared with low–carbon MgO–C refractories. The superior corrosion resistance was primarily attributed to the formation of a dense protective layer composed of MgO–MgAl2O4–Mg3B2O6, which was achieved at 1100 °C by combining Al3BC3–Al. These protective layers with enhanced diffusion barriers effectively impedes the penetration and solid solution of Ca and Fe ions, thereby also optimizing the slag viscosity. The self–healing capability of the novel MgO–Al3BC3 refractories further enhances their corrosion resistance.

Assessment of Groundwater Stability Using Corrosion and Scaling Tendency Indices on Selected Springs in the Manga Region in Nyamira County, Kenya

Assessment of Groundwater Stability Using Corrosion and Scaling Tendency Indices on Selected Springs in the Manga Region in Nyamira County, Kenya

Alternative Industrial Chrome-Free Alumina-Based Bricks for Copper Alloy Melting Furnaces

Abstract In this study, the corrosion resistance of alumina-based bricks against the slag of copper alloy melting furnaces was investigated. Four commercial chrome-free alumina bricks have been studied. Bulk density and apparent porosity measurements and phase analysis of the bricks were performed. The most important property, the slag corrosion resistance, was evaluated at the temperature of 1,200°C for 2 h. The microstructures of the bricks, their penetration depth, and corrosion index were evaluated. The results showed that two bricks showed acceptable corrosion resistance against the slag. The low corrosion index of these bricks was attributed to their aluminosilicate phases (sillimanite, or andalusite) and lower phosphate bonding; however, the problematic matter was the silicate phase, which showed lower resistance against the penetration of slag. It was observed that the aluminosilicate phase can improve the corrosion resistance through the reaction with slag, whereas the presence of large alumina aggregates can restrict the penetration of slag.

Torrefaction as a Way to Remove Chlorine and Improve the Energy Properties of Plant Biomass

This study characterizes and compares the physicochemical parameters of three types of biomass: giant miscanthus, wheat straw, and white willow. An analysis of the chlorine content in the biomass was determined using a 5E-FL2350 fluorine and chlorine analyzer. In addition, energy parameters characterizing the biomass were determined, such as the content of ash and volatile matter in the tested materials, using the LECO TGA 701 thermogravimetric analyzer. The carbon and hydrogen contents were tested using the LECO TruSpec CHN elementary organic analyzer. The calorific value was determined using the LECO AC 500 isoperibolic calorimeter. Based on the research results, it was concluded that the use of the biomass torrefaction process improves its energy parameters. In the long term, this will affect the maintenance of the technical and operational efficiency of devices, installations, and power boilers compared to the co-combustion of fresh biomass. The greatest differences in results were recorded in the case of chlorine content. Carrying out detailed tests on the material immediately after its harvest showed that the content of this element was about 70% higher than in the case of torrefied raw material. The presence of chlorine in alternative fuels is responsible for the formation of chloride corrosion. Its content can be up to five times higher compared to conventional energy sources. The degree of risk of chloride corrosion of the selected elements of devices and installations is assessed on the basis of the so-called “chlorine corrosion index”.

Optimization of corrosion resistance and mechanical properties of Al2O3‐Cr2O3 refractories for waste incinerator

AbstractThe corrosion resistance and mechanical properties directly affects the operation and service life of Al2O3‐Cr2O3 refractories used in waste incinerators. In this study, ZrO2 particles were introduced via vacuum impregnation to adjust microstructure and properties of Al2O3‐Cr2O3 refractories. The results showed that the impregnated ZrO2 particles and increasing impregnation times resulted in the decreased median pore size and increased compactness, and mechanical strengths of refractories were elevated from the inhibited cracks propagation by ZrO2 particles. The decreased amounts of large pores and increased amounts of small pores from the filled ZrO2 particles inhibited penetration of low melting point phases, and the formed CaZrO3 phase from the reactions between corrosion reagent and ZrO2 particles increased the viscosity of penetrated corrosion reagent, resulting in the decreased penetration index from 8.57% to 2.58%. Meanwhile, the filled ZrO2 particles around alumina particles prevented reactions between molten corrosion reagent and alumina, leading to the decreased corrosion index from 3.78% to .74%. The decreased pore size and formation of CaZrO3 phase were primary factors that enhanced the penetration resistance. And formation of wrapped layers from ZrO2 particles around alumina particles presented prominent effects on the strengthened corrosion resistance of Al2O3‐Cr2O3 refractories.

Investigating Effects of Reverse Osmosis-Treated Water on the Corrosion Rate of Chains in Armoured Face Conveyor for Longwall Mining

Premature failure of armoured face conveyor (AFC) chains due to corrosion is a significant proportion of the unplanned downtime experienced on longwall equipment. The AFC chains are constantly in contact with water and wet coal. The premature failure issue of AFC chains has become more prominent since the introduction of longwall top-coal caving with its additional AFC. Reverse osmosis (RO) is a popular water treatment method for reducing salinity and dissolved solids, but its impact on the corrosion of the AFC chains is unclear. This study has been commissioned to investigate the direct effects of RO water on the corrosion of AFC chains. An immersion test was carried out using AFC chain steel submerged in two water samples: untreated dam water and treated water from an RO treatment plant. Elemental analysis was conducted for both water samples, and four corrosion indices were measured for both water samples. The RO water more vigorously dissolves calcium carbonate scales leading to increased corrosion of the AFC chains although the dam water has much higher levels of calcium, chloride, sulphate, sodium, and magnesium. Bicarbonate ions are the main alkaline factor of water that provides the buffering capacity to acids. Decreased alkalinity without balancing other ions in water causes high corrosivity and decreased scaling tendencies.

Detection and localization of corrosion using identical-group- velocity Lamb wave modes

ABSTRACT Multimodal is the prominent characteristic of Lamb waves, which means a variety of Lamb wave modes propagate in the structure and each of them has unique propagation behaviour. For a wideband multimodal Lamb wave signal, it is possible that many different modes share the same group velocity at some frequency points, while their dispersion behaviours change differently to thickness variation. In this study, the diversity and difference of the interaction between the corrosion and Lamb wave modes are investigated. On this basis, a corrosion index (CI) is established to evaluate the time gap between two modes at their identical group velocity points. The simulation results show that the CI value of a corroded path is obviously larger than that of a healthy path, indicating the presence of the damage, which is independent of any base-line signal. Furthermore, the new reconstruction algorithm for the probabilistic inspection of damage (RAPID) was proposed, where the signal difference coefficient was replaced by the CI to visualise damage location. The experimental results demonstrate the effectiveness of the proposed multimodal Lamb wave baseline-free damage detection method.

Evaluating the corrosion index of DTPA at different conditions - key of improving the performance of chelating agents in field treatments

Solutions that rely on chelating agent are widely implemented in upstream oil and gas field processes, due to their unique performance and their ability of capturing specific ions. There is a need to fully understand the impact of chelating agents on operational tools at different conditions. A variety of complications in processing chelating agents are related to their corrosion behavior and iron control capability. In this work, the static corrosion index of chelating agents (DTPA, EDTA, and GLDA) was investigated experimentally over the pH range of 4–12 using different basic media, where the impact of the courter ion (potassium or sodium) is in focus. The impact of preparing the chelating solutions differently on the rate of corrosion was explored. Essentially, the aim was to adjust the pH differently (upwards or downwards, referred to as “Basification” and “Acidification” lines, respectively). The tests were conducted using aging cell isolated by Teflon liner at 500 psi and different temperatures (200 °F, 250 °F and 310 °F). The results show that the dissolution rate of the iron by the chelating agent was influenced considerably by preparation route, that is solutions with the same pH value do not result in the same dissolution rate. For instance, at pH 4.4 and 310 °F test conditions, the corrosion index for the DTPA-K (Basification) was approximately 0.20 lb/ft2, meanwhile, the prepared sample in acidification line (DTPA-K) yielded 0.15 lb/ft2 at same test conditions. Similar observation was exhibited for the other samples. The reaction rate in the upwards preparation process (Basification line) was higher than the rate yielded in the downwards preparation process (Acidification line). We propose a mechanism that accounts the observations that is rooted in the ability of binding external species such as Na+, K+ and Cl− to the central system (either the chelating agent itself or the Fe2+ chelating agent adduct). The mechanism is supported by a series of ab initio calculations.

Assessment of the hydrogeochemistry of shallow water aquifers using corrosion indices and geospatial techniques in the regions of the Brahmaputra river basin, India

Assesment of hydrogeochemistry of shallow water aquifers using corrosion indices and geospatial techniques with significant outcome and recommendations in the regions of the Brahmaputra river basin, India.

Hydrogeochemical investigation and groundwater quality assessment toward ‘smart city planning in a coastal aquifer, India

Abstract This paper aims to understand the general background of groundwater quality that must be considered for the 'smart city' planning of Surat city. Twenty-Six water samples collected from bore wells of the city were analyzed. The results showed that water is alkaline, as pH varies from 7.6 to 9.2. The concentration of Cl− and Na+ are correlated with EC. The highest levels of Cl− and Na+ are found near the coastal region (predominantly northwestern); Piper trilinear diagram shows 52% of samples are Na-HCO3− type and 48% NaCl type. WQI shows that most samples are potable for drinking, but a few samples from the western part are not suitable for drinking. SAR, Na%, and PI results show that most samples are suitable for irrigation. The corrosivity index indicates that 50% of samples have a CR > 1(unsafe zone), and the rest are within the safe limit. The relationship of WQI with different water quality parameters revealed that groundwater quality has deteriorated in the city's western part, which may be due to seawater intrusion in the aquifer. This work gives a basic idea of groundwater quality, which will help make Surat a smart city.

Minimizing the negative impacts of rebar stored in the Persian Gulf on reinforced concrete corrosion

The study aims to ascertain the impact of improving concrete quality on decreasing the unfavorable impact of pre-rusted rebar on steel corrosion in reinforced concrete. Steel corrosion was assessed using half-cell potential and corrosion rate intensity tests, and concrete quality was assessed using electrical resistance measure and rapid chloride permeability test (RCPT). The efficiency of each element in influencing the steel corrosion in reinforced concrete was determined by the factors of the impact of rebar surface conditions and concrete quality on corrosion. The results showed that when using normal rebar, the effect of concrete quality index and rebar surface conditions on corrosion was 40.11% and 0.24%, and when using rebar with a corrosion index (CI)=11 was 1.25 % and 55.57%, respectively. Therefore, by increasing the pre-rusted rebar surface, the effect of concrete quality on corrosion reduces, and the effect of rebar surface conditions increases. In this study, until CI=7, the influence of the concrete quality index was more significant on corrosion than rebar surface conditions, followed by a reverse trend. Therefore, until CI=7, the concrete quality was the dominant factor in determining the corrosion rate intensity. By increasing the corrosion index, the steel corrosion rate intensity in reinforced concrete depends on the rebar surface conditions, and by increasing the concrete quality, these adverse effects cannot be reduced to a large extent.

Improvement of corrosion and stress corrosion properties of magnesium alloys by coating aluminum with the electric arc spray method

AbstractIn this study, corrosion and stress corrosion behaviors of AZ31, AZ61, and AZ91 magnesium alloys coated with aluminum by the electric arc spray method were investigated in 3.5 wt.% NaCl solution. Structural properties of coated materials were investigated by scanning electron microscopy (SEM), energy dispersive X‐ray analysis, and X‐ray diffraction. Electrochemical properties were determined using the potentiodynamic polarization method in 3.5 wt.% NaCl solution. Potentiodynamic polarization curves showed that corrosion current density values did not change with coating in aluminum‐coated samples by the electric arc spray method. In contrast, corrosion potential value increased toward positive values. Slow strain rate test (SSRT) was used to determine the stress corrosion behavior and stress corrosion indexes (ISCC), ultimate tensile strength (UTS), and elongation of AZ31, AZ61, and AZ91 magnesium (Mg) alloys were determined. As a result of the SSRT, the aluminum coating process decreased significantly the stress corrosion indexes of AZ31, AZ61, and AZ91 Mg alloys. The fracture of surface images was also examined in the SEM, and both intergranular and transgranular stress corrosion cracking were observed in all three alloys.

Investigation of Corrosion and Scaling Potential in Drinking Water in Rafsanjan, Iran

Introduction: Corrosion and scaling are important factors affecting drinking water quality, causing health and economic problems. This study aimed to investigate the indicators of corrosion and scaling in Rafsanjan drinking water.
 Materials and Methods: The present descriptive cross-sectional study was conducted in winter 2018 and spring 2019 in Rafsanjan. The 56 samples were randomly taken from the drinking water distribution and transmission networks. Physicochemical parameters, such as pH, temperature, total dissolved solids (TDS), total hardness (TH), calcium hardness (CH), electrical conductivity (EC), and alkalinity were measured. Finally, corrosion and scaling indices, including langelier index (LI), ryznar index (RI), aggressiveness index (AI), and Puckorius index (PI) were calculated and analyzed.
 Results: The mean temperature, pH, CH, TH, TDS, alkalinity, and EC were 17.79 ± 0.80 °C, 8.08 ± 0.11, 56.34 ± 2.72 mg/L.CaCO3, 140.86 ± 6.81 mg/L.CaCO3, 530 ± 110 mg/L, 181.21 ± 13.65 mg/L, and 840 ± 180 µs/cm, respectively. The mean corrosion and scaling indices, including LI = 0.18 ± 0.12, RI = 7.72 ± 0.14, AI = 12.09 ± 0.11, and finally PI = 7.96 ± 0.10 were obtained.
 Conclusion: Based on the obtained data, drinking water in the transmission and distribution network of Rafsanjan has scaling properties. Water scaling and deposition causes problems, such as blockage of water transmission and distribution pipes, reduction of flow rate and increase of pressure drop in the network, and finally increase of water facilities operation costs. Therefore, measures should be considered to control the scaling of water in this region.