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•An in-situ and real-time electrochemical monitoring of flow-induced corrosion of Mg alloy is designed in a vascular bioreactor.•Effect of hydrodynamics on corrosion kinetics, types, ...rates and products is analyzed.•Flow accelerates mass and electron transfer, leading to an increase in uniform and localized corrosions.•Flow increases not only the thickness of uniform corrosion product layer, but the removal rate of localized corrosion products.•Electrochemical impedance spectroscopy and linear polarization-measured polarization resistances provide a consistent correlation to corrosion rate calculated by computed tomography.
An in-situ and real-time electrochemical study in a vascular bioreactor was designed to analyze corrosion mechanism of magnesium alloy (MgZnCa) under mimetic hydrodynamic conditions. Effect of hydrodynamics on corrosion kinetics, types, rates and products was analyzed. Flow-induced shear stress (FISS) accelerated mass and electron transfer, leading to an increase in uniform and localized corrosions. FISS increased the thickness of uniform corrosion layer, but filiform corrosion decreased this layer resistance at high FISS conditions. FISS also increased the removal rate of localized corrosion products. Impedance-estimated and linear polarization-measured polarization resistances provided a consistent correlation to corrosion rate calculated by computed tomography.
•Oil leakages of corroded subsea pipeline occurred after 27 years in service.•The presence of chloride ions in the water phase promoted flow-induced corrosion.•The corrosion rate could be reduced by ...controlling flow patterns.
Failure of a subsea crude oil API 5L X52 steel pipeline which led to oil leakage has been reported to occur after 27 years in service. Some leaks were found to form at the bottom of the horizontal API 5L X52 steel pipeline near an elbow section which connected the pipeline to a riser. The present investigation aims to analyze the main cause of failure by conducting standard failure analysis methods including visual examination, chemical and mechanical characterizations, metallurgical examinations using optical microscopy in combination with scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) analysis and corrosion test using a three-electrode potential technique. Results of this investigation suggest that the cause of failure is electrochemical corrosion combined with mechanical process known as flow-induced corrosion. The failure mechanism is discussed with specific attentions are paid to fluid flow rate and chloride-containing water phase.
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•Copper corrosion in aqueous solution with chloride ions is studied by MD simulations.•The effect of surface defects on the carrion mechanisms at nanoscale is ...investigated.•Acceleration of corrosion, with the flow of corrosive substance is studied.
Metal aqueous corrosion is a common electrochemical phenomenon. Nonetheless, the metal corrosion simulations at the atomistic scale have not been well-established yet. In this study, several copper corrosion cases in aqueous solution with chloride ions are studied with molecular dynamics, especially the flow induced corrosion is studied for the first time to the best of our knowledge. The copper corrosion in two kinds of solutions, which are HCl and chloride ions solutions, are simulated with pre-developed reactive force field (ReaxFF) method. Here, particles diffusion, bonding among elements, and charge evolution are analyzed to understand the mechanisms of the cases. It is found that the electrolyte flowing and initial Cu surface can accelerate the corrosion process, illustrated by higher mean-squared displacement (MSD) and Cu average charge. Moreover, the initial rough surface has different effects for different electrolyte concentrations. This work may provide important references for fundamental understanding the mechanisms of copper corrosion in chloride-containing solutions at nanosized scale.
In CO2 environments, an increase in the temperature can influence carbon steel flow-induced corrosion (FIC) and erosion-corrosion (EC) degradation processes. Increasing temperature typically results ...in the acceleration of electrochemical degradation mechanisms in the absence of protective corrosion product layers. Furthermore, the presence of sand in corrosive process fluids could aggravate the service conditions. Although protective iron carbonate (FeCO3) film or/and corrosion inhibitors are capable of suppressing corrosion in CO2-containing environments typical of oil and gas production, their ability to suppress degradation and their associated mechanisms in erosion-corrosion environments is less understood. This work focuses on understanding the ability of FeCO3 to protect the steel surface in the absence and presence of corrosion inhibitor and their interactions in flow-induced and erosion-corrosion systems at 60 °C. The effect of the temperature increase is investigated based on results obtained in a previous study performed at 25 °C. FeCO3 filmed carbon steel specimens were developed using an autoclave at 60 °C, pH 6.6 and 30 bar in a 1.5 wt% NaCl CO2-saturated solution over 48 h. The FeCO3 covered specimens were evaluated in FIC and EC environments at 60 °C and a flow velocity of 15 m/s in the presence and absence of 1000 mg/L sand and 100 ppm of a commercially available corrosion inhibitor. Results indicate that the sole presence of an FeCO3 layer is not sufficient to retard the corrosive process of carbon steel at 60 °C under EC conditions. However, the commercial corrosion inhibitor was observed to worked synergistically with the FeCO3 layer to reduce the corrosion degradation component in both the presence and absence of sand particles. The erosion component is also reduced in erosion-corrosion environments as a result of the combined presence of FeCO3 and corrosion inhibitor.
•Inhibition action is maintained whether higher temperature.•Sole FeCO3 layer do not attenuate the corrosive process in EC tests.•Inhibitor and FeCO3 layer work synergistically reducing corrosion rate.•FeCO3 layer is not soluble at 60 °C within the operation window of FIC and EC tests.
The flow-induced corrosion in gas-liquid flow usually occurs in the petrochemical and transportation industries, which has become a hot topic, especially for the elbow system. In this paper, a series ...of simulations using the VOF method and SST k-ω turbulence models were carried out to investigate the temporal and spatial distributions of the water wetting process in the elbow system. Combined with experiments, the relationship between the dynamic hydrophilic process and the corrosion mechanism was revealed. The results show that there is a stratified flow in the pipe at low speed. Wetness is always present in the inner wall of the elbow, and the corrosion rate reduces as the axial angle increases. As the velocity increases, the flow pattern changes to wave flow. Part of the water in the inner wall is entrained into the gas phase and thrown out onto the outer wall to form the water wetting. The location of maximum wall shear stress is transferred to outer wall, causing an increment of corrosion rate. The corrosion rate of the outer wall increases with the axial angle.
•The potential decreases and the current density increases with particle impact.•The final OCP after passivation is lower than initial result before impingement.•The oxygen concentration has two peak ...values when particle impacts on the surface.•The higher velocity of particle is, the lower passivation rate becomes in unit time.
Data from a standard laboratory test including open-circuit potential (OCP) and current density monitoring is used to study the effect of fracturing proppant impingement on corrosion of tubular steel. A solid-liquid flow simulation is performed to obtain some parameters of particle movement and oxygen mass transfer near the metal surface. The results show that the electrochemical reaction includes passivation, activation and repassivation during a particle impact on the metal surface. Once the metal surface is in the activated state, the potential and anode current density is controlled by the oxygen concentration in the boundary layer and repassivation rate of metal surface. The increase of particle impact velocity accelerates the transmission of corrosion reactants and creates deeper impact craters on metal surface, resulting in the increase of current density. Meanwhile, the high speed particle impingement causes some platelets and extruding lips and thus weakens the surface corrosion resistance of stainless steel.
This reprint aims to promote and disseminate applied research in the field of corrosion of steel structures and technological equipment. Within the text, the focus is firmly placed on the detailed ...study of corrosion processes affected by specific environments, as well as on the effects of corrosion damage on the reliability and service life of structural components and technological equipment. Special attention is paid to the study of the impact of corrosion processes on pipelines.
This reprint aims to promote and disseminate applied research in the field of corrosion of steel structures and technological equipment. Within the text, the focus is firmly placed on the detailed ...study of corrosion processes affected by specific environments, as well as on the effects of corrosion damage on the reliability and service life of structural components and technological equipment. Special attention is paid to the study of the impact of corrosion processes on pipelines.
The high pressure and high temperature (HPHT) flow solution containing various gases and Cl− ions is one of the corrosive environments in the use of oilfield tubing and casing. The changing external ...environment and complex reaction processes are the main factors restricting research into this type of corrosion. To study the corrosion mechanism in the coexistence of O2 and CO2 in a flowing medium, a HPHT flow experiment was used to simulate the corrosion process of N80 steel in a complex downhole environment. After the test, the material corrosion rate, surface morphology, micromorphology, and corrosion product composition were tested. Results showed that corrosion of tubing material in a coexisting environment was significantly affected by temperature and gas concentration. The addition of O2 changes the structure of the original CO2 corrosion product and the corrosion process, thereby affecting the corrosion law, especially at high temperatures. Meanwhile, the flowing boundary layer and temperature changed the gas concentration near the wall, which changed the corrosion priority and intermediate products on the metal surface. These high temperature corrosion conclusions can provide references for the anticorrosion construction work of downhole pipe strings.
An investigation was conducted to assess the performance of a commercially available high shear carbon dioxide (CO2) corrosion inhibitor in a series of flow-induced corrosion and erosion–corrosion ...environments. The purpose of the study was to understand the role that high shear stress and sand particle impingement play in influencing the in-situ corrosion rate of API 5L X65 carbon steel in blank and inhibited conditions. Tests were conducted at 45°C in CO2-saturated conditions using a rotating cylinder electrode (RCE) for low shear stress tests (18–260Pa) and a submerged impinging jet (SIJ) for high shear environments (104–740Pa). The inhibitor was studied at concentrations of 0, 25, 50, 75 and 100ppm. The application of computational fluid dynamics to model the SIJ and the use of ring shaped samples allowed for an accurate prediction of shear stress across the specimen surface that could be correlated with in-situ corrosion rate and inhibitor efficiency over a range of concentrations. The incorporation of 500mg/L of sand to the system helped to quantify the increase of the in-situ corrosion rate due to the impingement of the particles. All corrosion rates were determined through the application of linear polarization measurements throughout the duration of the test. Post-test analysis of the material degradation mechanisms was examined using scanning electron microscopy (SEM).
•We examine the shear stress and sand particle impingement effects in blank and inhibited CO2 environment.•Degradation rates increase as the shear stress increases and in the presence of sand particles.•Introduction of inhibitor suppresses the degradation rates.•Establish the transfer phenomena that account for the corrosion rates.
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