Experiment and numerical simulation of distribution law of waterbased corrosion inhibitor in natural gas gathering and transportation pipeline

The transmission medium of natural gas gathering and transportation pipelines usually contains cor-rosive gases,which will cause serious corrosion on the inner wall of the pipelines when they coexist with water.Therefore,it is necessary to add corrosion inhibitor to form a protective film to protect the pipeline.The distribution of corrosion inhibitors in a gathering and transportation pipeline in Moxi gas field was studied by combining experiment and simulation.The Pearson function was used to calculate the experimental and simulation results,and the correlation was more than 80%,indicating a high degree of agreement.The simulation results show that:①The larger the pipe angle,filling speed and gas flow rate,the smaller the particle size,the better the distribution of corrosion inhibitor particles in the pipe.The filling amount will affect the concentration,but the distribution trend is unchanged;②A method to determine the filling mode based on the loss was proposed,and for this pipeline,the loss of corrosion inhibitor was determined to be 5.31×10^(-3) kg/s,and the flling amount was recommended to be adjusted to 2o L/h,which has certain guiding significance for the actual flling strategy of pipeline corrosion inhibitor.

Active corrosion protection of super-hydrophobic corrosion inhibitor intercalated Mg-Al layered double hydroxide coating on AZ31 magnesium alloy

Magnesium alloys,the advanced lightweight structural materials,have been successfully applied in the manufacturing field.Unfortunately,their poor corrosion resistance restrains the potential wide applications.In this work,anti-corrosion coatings were fabricated via the insitu growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide(Mg-Al LDH)on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating.SEM,XRD,EDS,FTIR,XPS and contact angle test were conducted to analyze physical/chemical features of these coatings.Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings.Surprisingly,Mg-Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance(99.99%)due to the multicomponent synergistic effect such as the physical protection of Mg-Al LDH,the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid.This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field.

Release rate kinetics of corrosion inhibitor loaded halloysite nanotube-based anticorrosion coatings on magnesium alloy AZ91D

Halloysite nanotubes were used as nanocontainers to hold corrosion inhibitors such as Ce^(3+)-Zr^(4+),2-mercaptobenzothiazole and 8-hydroxyquinoline in their lumen.An acid assisted etching of the nanotubes was carried out with a view to increase the lumen diameter and thereby,increase the amount of loading of the corrosion inhibitor.The morphology of as-received and etched halloysite nanotubes was ob-served using TEM analysis.The loading of corrosion inhibitors was confirmed using SEM-EDS and BET analysis.Polymeric microcapsules were used as capping agents for the ends of the loaded HNTs following which,they were dispersed into a hybrid sol-gel silica matrix.Dip coating method was used to generate coatings on AZ91D substrates followed by heat treatment at 130℃ for 1 h.The release rate kinetics of corrosion inhibitors from as-received and etched nanotubes was investigated in buffer solutions of 3.5 wt%NaCl at different pH.The release mechanism of corrosion inhibitors from the HNT lumen was validated using various semi-empirical models.Coatings were also evaluated for their corrosion protection ability using electrochemical techniques after exposure to 3.5 wt%NaCl solution for 120 h.Coatings generated using Ce^(3+)-Zr^(4+)loaded into as-received halloysite nanotubes have shown more effective corrosion protection when compared to other corrosion inhibitors after 120 h exposure to the corrosive medium.

Insights into the multiple applications of modified polyacrylamide as oilfield corrosion inhibitor and water phase tackifier

In order to obtain a multifunctional oilfield agent with both corrosion inhibition and oil displacement functions,a polymer with benzene ring structures is synthesized based on polyacrylamide(PAM)and used as inhibitor for the first time.Methods including electrochemistry,weight loss and theoretical calculations are used to study the inhibition effect for P110 steel in 1.0 M HCl.The experimental results show that the modified polymer poly-(Z)-N-benzylidenepropionamide(PBAM)has excellent inhibition effects,and the maximum efficiency can reach 90.62%in impedance spectroscopy tests.The benzene ring structure added in the modified polymer providesπelectrons for the adsorption of inhibitor on metal surface,strengthens the adsorption,and thus brings a better corrosion inhibition effect.In addition to the corrosion inhibition performance,the viscosity-increasing effect of PBAM is evaluated.The results show that the addition of benzene ring not only enhances the corrosion inhibition effect,but also brings temperature resistance to the polymer.However,the salt tolerance of the polymer is affected,the synthesized PBAM which viscosity can above 500 m Pa s at 140℃ is suitable for high temperature and low salinity environment.The modified polyacrylamide has satisfactory corrosion inhibition and oil displacement performance,which provides a new idea for the development of oilfield chemistry.

The Use of Sodium Silicate as a Corrosion Inhibitor in a Saline Drilling Fluid: A Nonaggressive Option to the Environment

The function of a corrosion inhibitor in drilling mud compositions is the corrosion protection of the equipment involved in drilling operations. Many compositions involve environmentally several products such as fatty amines of high molecular weight, polyoxylated amines, amides, imidazolines, nitrogen heterocyclic products, etc. The potential advantages of the use of silicates are the effective protection of carbon steel, especially in aerated saline fluids, low costs and non-aggressive behavior to environment. Gravimetric and electrochemical tests were carried out using an aerated solution of 3.5% NaCl and the addition of sodium silicate (Na2SiO3·9H2O) as a corrosion inhibitor at concentrations of 250 to 2000 mg/L. The efficiencies of the corrosion protection of carbon steel using silicate concentrations greater than 1250 mg/L were greater than 92%.

Co Complexes as a Corrosion Inhibitor for 316 L Stainless Steel in H2SO4 Solution

The effect of Co complexes with a Schiff base ligand on the electrochemical corrosion behavior of 316 L SS in 0.1 M H2SO4 at 25℃ has been investigated at various inhibitor concentration using electrochemical techniques (impedance spectroscopy (EIS), polarization curves). Corrosion measurements indicate that Co complex act as moderately inhibitors. Results revealed that increasing the concentration of Co complex increases the corresponding IE% values till 100 ppm. Co complex acts as mixed type inhibitors with predominant effect on the anodic dissolution of iron. Adsorption studies showed that the process follows Langmuir adsorption isotherm.

1-Hydroxyethylidene-1,1-diphosphonic Acid (HEDP) as a Corrosion Inhibitor of AISI 304 Stainless Steel in a Medium Containing Chloride and Sulfide Ions in the Presence of Different Metallic Cations

The novelty of this paper is the analysis in a medium containing sulfide ion due to the generation of this ion in petroleum industries, in the refining stage (the sulfide ion is also present on the produced water). The performance of 1-hydroxyethylidene-1,1-diphosphonic acid inhibitor (HEDP) was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurements in a dissolution of AISI 304 stainless steel immersed in a solution containing chloride and sulfide ions. The protection of the stainless was increased with the addition of divalent cations (Ca2+, Zn2+, and Mg2+). Potentiodynamic polarization studies have shown that the inhibitor alone has anodic protection, but the addition of Ca2+ (10 mg·L-1) favors the cathodic protection, and the addition of Zn2+ (20 mg·L-1) and Mg2+ (10 mg·L-1) mixed-type is observed. Electrochemical impedance spectroscopy was performed at three distinct potentials: -0.3 [V vs. SCE], Ecorr [V vs. SCE], and 0.1 [V vs. SCE]. This revealed that calcium is responsible for favoring the formation of the film and the other elements (zinc and magnesium) favor the stabilization of the protective film. Scanning electron microscopy analysis revealed that the addition of cations provided the adsorption of HEDP on the metal surface. Weight loss results showed that the presence of zinc in a solution containing HEDP favored greater inhibitor efficiency (Zn2+ ηm = 85.2% and for Mg2+ ηm = 70.4%).

Use of Corrosion Inhibitor in Solid Form to Prevent Internal Corrosion of Pipelines and Acidification Process

Use of corrosion inhibitors in solid form promotes the development of a new technique for internal corrosion protection of oil & gas pipelines and operations of oil wells acidification, because the controlled dissolution of the corrosion inhibitor forms a surface on metallic parts, a protective film that prevents or minimizes undesirable reactions to corrosion. In addition, this technique has important social and environmental benefits, ensures the operator has a lower risk of contamination when handling the product, changes the type of industrial packing, facilitates transportation, reduces solvent use and consequently reduces the waste that normally results from the use of inhibitors. The purpose of this article is to present a class of solid corrosion inhibitor tested in the laboratory and offer proposals for its application in industrial pipes such as gas and oil pipelines.

Experimental and quantum chemical studies of carboxylates as corrosion inhibitors for AM50 alloy in pH neutral NaCl solution

Sodium salts of mono-and di-carboxylic acids(glycolic,fumaric and benzoic acid)were studied as corrosion inhibitors for AM50 alloy in pH neutral aqueous NaCl environment.Hydrogen evolution,electrochemical and surface characterization techniques were employed to reveal their corrosion inhibition mechanism,whilst the molecular features of inhibitors were investigated by quantum chemical calculation.All inhibitors reduced anodic dissolution of AM50 and their efficiency generally increased with time and concentration from 5 mM to 100 mM.The inhibition mechanism can be described as physisorption of inhibitive molecules on the surface of the intrinsic oxide layer followed by chemisorption with Mg^(2+)and Al^(3+),and the difference in inhibition action among these inhibitors was explained on the molecular scale.

Investigation of Aloe lateritia Gel as Corrosion Inhibitor for Mild Steel in 2 M HNO3 and 1 M H2SO4 Media

Corrsion inhibition of Aloe lateritia gel for Mild steel in 2 M HNO3 and 1 M H2SO4 solutions was investigated by potentiodynamic polarization, Scanning electron microscopy (SEM) and Foutier transform infrared (FT-IR). Inhibition efficiency increased with the increase of the concentration of the gel. The optimal concentration of the gel gives maximum inhibition efficiency of 77.4% and 70.3% in 1 M H2SO4 and 2 M HNO3 respectively. Polarization plots shows that, the gel works as a mixed type inhibitor altering both cathodic and anodic reaction. SEM proves the uniform and pitting corrosion at the surface of Mild steel in 1 M H2SO4 and 2 M HNO3 respectively. Using FT-IR potential function groups from pure gel and some stretch shift was observed from corrosion product and some stretch shift from corrosion products was observed.

Orange Peel Extract Mediated Silver Nanofluid as Corrosion Inhibitor for X80 Steel in Simulated Oilfield Scale Dissolver

Silver nanofluid was prepared by bio-reduction reaction between orange peels extracts(OPE)and silver nitrate and characterized by spectroscopic and microscopic techniques.Colloidal nanoparticles of sizes between 40-50 nm and spherical shape were obtained.The nanofluid was applied as anticorrosion additive to inhibit corrosion of X80 steel in simulated oilfield scale dissolver solution(1.0 M HCl)at various temperatures.The nanofluid(OPE-AgNPs)was 98.9% and 84.3% efficient at 30℃ and 60 ℃ respectively as determined by weight loss measurement.In comparison with OPE,OPE-AgNPs shows better corrosion inhibition and higher resistance to thermal degradation.Some kinetic and thermodynamic models were used to characterize the inhibition process.OPE-AgNPs could be optimized and used as alternative anticorrosion additive for scale dissolution liquor in the industry.

Effect of Corrosion Inhibitor Used in Surface Treatment on the Anticorrosive Performance of an Epoxy Paint System

The mechanism of corrosion is mainly sustained by an electrochemical process, in which anodic and cathodic reactions take place, keeping their kinetics alive by electrons and ions fluxes. Several specific conditions can accelerate corrosion processes. When studying anticorrosive coatings, one of them is the contamination of metallic surface by soluble salts prior to coating, leading to premature failure of the paint system due to corrosion between the metallic surface and the coating. So the surface preparation step prior to coating is a procedure of great importance to the coating anticorrosive performance. The aim of this step is to clean the surface by removing visible and non-visible contaminants. Usually, wet abrasive blasting methods are the most efficient ones to achieve the latter objective, because they may clean the surface, create a surface roughness and also remove the non-visible contaminants, as they use water as a media. On the other hand, evaporation of water after blasting may create flash rust and to avoid this, it is common to use corrosion inhibitors in the water of wet blasting methods. In this paper, the use of sodium tetraborate (borax) as a corrosion inhibitor in wet abrasive blasting is discussed. Electrochemical measurements and mass loss tests show that a borax content of 1% in a saline solution has the best inhibitory action over carbon steel and zinc surfaces, allowing postponing for the painting step some time. However, residual borax left on the surface generated blistering and corrosion under coating, during accelerated corrosion test in a humidity condensation chamber. Electrochemical impedance spectroscopy confirmed that borax accelerated the permeation of water through the coating, downgrading the anticorrosive performance of the paint system.

Instantly Investigating the Adsorption of Polymeric Corrosion Inhibitors on Magnesium Alloys by Surface Analysis under Ambient Conditions

Surface engineering of magnesium alloys requires adequate strategies, processes and materials permitting corrosion protection. Liquid formulations containing corrosion inhibitors often are to be optimized according to the demands of the respective substrate and following the service conditions during its application. As an interdisciplinary approach, a combination of several techniques for instantly monitoring or elaborately analyzing the surface state of magnesium was accomplished in order to characterize the performance of new adsorbing sustainable amphiphilic polymers which recently were developed to facilitate a multi-metal corrosion protection approach. The application of established techniques like Contact Angle measurements and X-ray Photoelectron Spectroscopy investigations was supplemented by introducing related and yet faster online-capable and larger-scale techniques like Aerosol Wetting Test and Optically Stimulated Electron Emission. Moreover, an inexpensive setup was configured for scaling the inset and the extent of degradation processes which occur at local electrochemical circuits and lead to hydrogen bubble formation. Using these analytical tools, changes of the surface state of emeried AM50 samples were investigated. Even in contact with water, being a moderate corrosive medium, the online techniques facilitated detecting surface degradation of the unprotected magnesium alloy within some seconds. In contrast, following contact with a 1 weight% formulation of a polymeric corrosion inhibitor, surface monitoring indicated a delay of the onset of degradation processes by approximately two orders of magnitude in time. Mainly based on the spectroscopic investigations, the corrosion inhibiting effects of the investigated polymer are attributed to the adsorption of a primary polymer layer with a thickness of a few nanometers which occurs within some seconds. Immersion of magnesium for several hours brings up a protective film with around ten nanometers thickness.

Corrosion behavior of Fe–Cr–Ni based alloys exposed to molten MgCl_(2)–KCl–NaCl salt with over-added Mg corrosion inhibitor

MgCl_(2)–NaCl–KCl salts mixture shows great potential as a high-temperature(>700°C)thermal energy storage material in next-generation concentrated solar power plants.Adding Mg into molten MgCl_(2)–NaCl–KCl salt as a corrosion inhibitor is one of the most effective and cost-effective methods to mitigate the molten salt corrosion of commercial Fe–Cr–Ni alloys.However,it is found in this work that both stainless steel 310 and Incoloy 800H samples were severely corroded after 500 h immersion test at 700°C when the alloy samples directly contacted with the over-added Mg in the liquid form.The corrosion attack is different from the classical impurity-driven corrosion in molten chloride salts found in previous work.Microscopic analysis indicates that Ni preferentially leaches out of alloy matrix due to the tendency to form MgNi_(2)/Mg_(2)Ni compounds.The Ni-depletion leads to the formation of a porous corrosion layer on both alloys,with the thickness around 204μm(stainless steel 310)and 1300μm(Incoloy 800H),respectively.These results suggest that direct contact of liquid Mg with Ni-containing alloys should be avoided during using Mg as a corrosion inhibitor for MgCl_(2)–NaCl–KCl or other chlorides for high temperature heat storage and transfer.

In-situ construction of grass-like hybrid architecture responsible for extraordinary corrosion performance: Experimental and theoretical approach

Despite the engineering potential by the co-existence of inorganic and organic substances to protect vulnerable metallic materials from corrosive environments,both their interaction and in-situ formation mechanism to induce the nature-inspired composite remained less understood.The present work used three distinctive mercaptobenzazole(MB)compounds working as corrosion inhibitors,such as 2-mercaptobenzoxazole(MBO),2-mercaptobenzothiazole(MBT),and 2-mercaptobenzimidazole(MBI)in a bid to understand how the geometrical structure arising from O,S,and N atoms affected the interaction toward inorganic layer.MB compounds that were used here to control the corrosion kinetics would be interacted readily with the pre-existing MgO layer fabricated by plasma electrolysis.This phenomenon triggered the nucleation of the root network since MB compounds were seen to be adsorbed actively on the defective surface through the active sites in MB compound.Then,the molecule with twin donor atoms adjacent to the mercapto-sites affected the facile growth of the grass-like structures with‘uniform’distribution via molecular self-assembly,which showed better corrosion performance than those with having dissimilar donor atoms with the inhibition efficiency(η)of 97%approximately.The formation mechanism underlying nucleation and growth behavior of MB molecule was discussed concerning the theoretical calculation of density functional theory.

Synthesis of mono and bis-4-methylpiperidiniummethyl-urea as corrosion inhibitors for steel in acidic media

Mono and bis-4-methylpiperidiniummethyl urea were synthesized,characterized and used as new corrosion inhibitors of mild steel in the acidic media.Inhibitory effect of two compounds on mild steel surface in the 1 mol·L^(–1 )sulphuric acid has been studied by a series of techniques,such as potentiodynamic polarization,weight loss and quantum chemical calculation methods.Potentiodynamic polarization measurements showed that two inhibitors are mixed type.All measurements showed that inhibition efficiencies enhanced with increase of inhibitor concentration.This reveals that inhibitive actions of inhibitors were mainly due to adsorption on mild steel surface.Density functional(DFT)calculations have been carried out for the title compounds by performing HF and DFT levels of theory using the standard 6-31G*basis set.

Corrosion inhibiting performance and mechanism of protic ionic liquids as green brass inhibitors in nitric acid

Four protic ionic liquids(ILs)were synthesized via a one-step method by using benzotriazole(BTA)and benzimidazole as cations,and benzenesulfonic acid and 2-naphthalenesulfonic acid(NSA)as anions.These ILs were used as green corrosion inhibitors for brass specimens in a nitric acid solution.The structure of the protic ILs was characterized by 1H-NMR,13C-NMR,and FT-IR spectroscopy.The effects of the IL structure,IL concentration,acid concentration,and corrosion time on the surface morphology of brass specimens and the inhibition efficiency(η%)of ILs were investigated by the weight loss method combined with SEM and EDS spectroscopy.Polarization curves and impedance spectroscopy were used to analyze the electrochemical corrosion inhibition mechanism of ILs.Results showed that IL synthesis was a proton transfer process,and the proton of the–SO3H group on NSA was deprived by BTA.IL[BTA][NSA],which had a high charge density and large conjugateπband,was the most effective inhibitor for brass corrosion.Theη%of[BTA][NSA]decreased with the increase in acid concentration and corrosion time,which showed an increment with the increase in[BTA][NSA]concentration.The higher theη%of[BTA][NSA]is,the smoother the surface of the brass specimens is,and the smaller the undistributed area of Cu element will be.Corrosion inhibiting mechanism from electrochemical analysis indicated that the addition of[BTA][NSA]increased the polarization resistance of the brass electrode significantly and suppressed both anodic and cathodic reactions.

Lignin-Phenylhydrazone as a Corrosion Inhibitor of API X52 Carbon Steel in 3.5%NaCl and 0.1 mol/L HCl Medium

The best alternative to fight against corrosion is the use of an inhibitor,the purpose of this work is the formulation of a new biomass-based molecule against corrosion of carbon steel.Lignin was extracted using the Kraft process and phenylhydrazine molecules have been scratched.The influence of the lignin-phenyl-hydrazone(LP)on the corrosion of carbon steel in salt and the acidic medium was studied by the polarization resistance,the potentiodynamic polarization,and the electrochemical impedance spectroscopy.The results of these tests reveal that the behavior of the inhibitor is a mixed type.The adsorption mechanism of the inhibitor follows the Langmuir isothermal model.Gibbs energy shows that the process of inhibition of carbon steel is spontaneous.The SEM confirms that the inhibitor reduces the corrosion of the steel and stops the corrosion pitting phenomenon.The modified lignin shown as a good corrosion inhibitor in acid medium is highly saline with an efficiency>96%.

Functionalized carbon dots for corrosion protection:Recent advances and future perspectives

Metal corrosion causes significant economic losses,safety issues,and environmental pollution.Hence,its prevention is of immense research interest.Carbon dots(CDs)are a new class of zero-dimensional carbon nanomaterials,which have been considered for corrosion protection applications in recent years due to their corrosion inhibition effect,fluorescence,low toxicity,facile chemical modification,and cost-effectiveness.This study provides a comprehensive overview of the synthesis,physical and chemical properties,and anticorrosion mechanisms of functionalized CDs.First,the corrosion inhibition performance of different types of CDs is introduced,followed by discussion on their application in the development of smart protective coatings with self-healing and/or self-reporting properties.The effective barrier formed by CDs in the coatings can inhibit the spread of local damage and achieve self-healing behavior.In addition,diverse functional groups on CDs can interact with Fe^(3+)and H^(+)ions generated during the corrosion process;this interaction changes their fluorescence,thereby demonstrating self-reporting behavior.Moreover,challenges and prospects for the development of CD-based corrosion protection systems are also presented.

Three novel dendritic chitosan derivatives for inhibiting acid corrosion of petroleum pipelines

In the process of exploration and development of oil and gas fields, the acidic environment of oil reservoir, production and transport processes cause corrosion of pipelines and equipment, resulting in huge economic losses and production safety risks. Corrosion inhibitors were widely used in oil industry because of simple operation process and economical. In this study, three environmentally friendly corrosion inhibitors were synthesized based on the natural polysaccharide chitosan. Corrosion inhibition of three dendritic chitosan derivatives (We name them BH, CH and DH) on mild steel in 1 mol/L HCl solution with natural ventilation system was evaluated by weight loss experiment, electrochemical analysis and surface morphology characterization. The experimental results showed that when the three dendritic chitosan derivatives added in the corrosive medium were 500 mg L^(−1), the corrosion inhibition efficiencies were all more than 80%. Based on quantum chemical calculation, inhibition mechanisms of three dendritic chitosan derivatives were investigated according to molecular structures. The results showed that the benzene ring, Schiff base and N atom contained in the molecule were the active centers of electron exchange, which were more likely to form a film on the carbon steel surface, thereby slowing or inhibiting corrosion. The results also predicted the corrosion inhibition effect BH > DH > CH, which was consistent with the experimental conclusion.