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This paper aims to explore the influence of CO₂ partial pressure, flow rate and water cut on N80 steel corrosion behaviors in the displacement process of oil in glutenite reservoir by CO₂ injection.

A self-made 3 L high-temperature and high-pressure autoclave was used to conduct corrosion simulation experiments of N80 steel in different CO₂ partial pressures, flow rates and water cut (the independently developed oil and water mixing approach can ensure the uniform mixing of oil and water in experiments). Techniques like weight loss and surface analysis were used to analyze the corrosion behaviors of N80 steel under different conditions.

Results showed that the average corrosion rate of N80 steel accelerated at varying degrees with the increase of CO₂ partial pressure, flow rate and water cut. Excluding that the samples showed uniform corrosion under the two conditions of 0.5MPa CO₂ partial pressure and static corrosion, they displayed mesa attack corrosion under other conditions. Besides, with the increase of CO₂ partial pressure, the pH value of solution dropped and the matrix corrosion speed rose, hence leading to the increased Fe²⁺ and CO₃²⁻ concentration. Meanwhile, a lowered pH value improved the FeCO₃ critical supersaturation, thereby leading to an increased nucleation rate/growth rate and ultimately causing the decrease of the dimension of FeCO₃ crystallites formed on the surface of the samples.

The results can be helpful in targeted anti-corrosion measures for CO₂/oil/water corrosive environment.

The purpose of this paper is to assess the serious corrosion problems of the water injection system on the offshore oil field and to study the type, and effect factors and mechanisms of corrosion on the offshore oil field in order to develop an effective corrosion inhibitor for the sea water injection system.

The corrosion of metal in a water injection system was studied by weight‐loss and electrochemical methods.The effect factors and mechanisms of corrosion on the offshore oil field were proposed from the trend of corrosion.

FeCO₃ is the main corrosion product in the water injection system of the Chengdao Offshore Oil Field. The corrosion rate of coupons in sea water injection systems reaches a maximum peak at a temperature of 50‐60°C. The corrosion rate of coupons exposed in all three water samples increased with an increase in the dissolved oxygen concentration. When the mixed ratio of sea water and produced water and well water is 1:3:1 or 1:2:2, the corrosion rate of carbon steel is lower than is the case in pure water. The electrochemical mechanism of corrosion indicates that corrosion in the well water, produced water, and sea water samples were all controlled by the oxygen absorption process, which controlled the cathodic reaction. The corrosion rate of coupons followed the ranking order: well water; produced water; sea water.

This paper provides the main corrosion product in the water injection system of the Chengdao Offshore Oil Field, and provides new information on the effect factors and mechanisms of corrosion on the offshore oil field.

The purpose of this paper is to implement the corrosion protection method for steel pipes used in a municipal water-pipe network. Results of an inhibitor protection system installed on the system are presented. Inhibitor protection was required due to the high corrosivity of the water collected by a surface intake, which had resulted in a large number of failures and low water quality, due to the presence of corrosion products.

To assess the effectiveness of protection and to control the optimum dose of the inhibitor dispensed, an automatic system of corrosion monitoring was used, together with an assessment of water corrosiveness based on measurements of physical and chemical properties of water.

Calcium polyphosphate, in the role of a non-toxic corrosion inhibitor, showed significant effectiveness as a anticorrosive and its results were fully noticeable after several years following the commencement of protection. Corrosion monitoring has shown that the effectiveness of inhibitor protection is highest in the summer season, when the water is characterised as being in its most corrosive form.

A reduction in the corrosion rate improves the quality of water and its chemical parameters fall within the standard range for water intended for consumption. The corrosion inhibitor action accelerates the formation of a layer limiting the corrosion rate. In this case, stable corrosion rates may be obtained after only the first year. In terms of the designing systems for monitoring corrosion in water systems, this is very important information as reliable results can be obtained for a long period after the launch of the system.

This paper aims to study flow‐induced corrosion mechanisms for carbon steel in high‐velocity flowing seawater and to explain corrosive phenomena.

An overall mathematical model for flow‐induced corrosion of carbon steel in high‐velocity flow seawater was established in a rotating disk apparatus using both numerical simulation and test methods. By studying the impact of turbulent flow using the kinetic energy of a turbulent approach and the effects of the computational near‐wall hydrodynamic parameters on corrosion rates, corrosion behavior and mechanism are discussed here. It is applicable in order to understand in depth the synergistic effect mechanism of flow‐induced corrosion.

It was found that it is scientific and reasonable to investigate carbon steel corrosion through correlation of the near‐wall hydrodynamic parameters, which can accurately describe the influence of fluid flow on corrosion. The computational corrosion rates obtained by this model are in good agreement with measured corrosion data. It is shown that serious flow‐induced corrosion is caused by the synergistic effect between the corrosion electrochemical factor and the hydrodynamic factor, while the corrosion electrochemical factor plays a dominant role in flow‐induced corrosion.

The corrosion kinetics and mechanism of metals in a high‐velocity flowing medium is discussed here. These results will help those interested in flow‐induced corrosion to understand in depth the type of issue.

The purpose of this paper is to evaluate the effect of seawater temperature on the corrosion behaviour of 90‐10 cupronickel alloys. Also, to investigate the effect of thiosulphate additions (one of the major sulphide oxidation products in seawater) on the alloy corrosion rate in seawater.

Potentiodynamic polarization measurement (DC) was used to estimate the corrosion rate of the cupronickel alloy in seawater with and without thiosulphate species (50‐650 ppm).

It was observed that the cupronickel alloy suffered accelerated corrosion as the seawater temperature was raised from 25 to 50 or 80°C. The increase in the corrosion rate was found to correspond well with the negative shift in the free corrosion potential. Thiosulphate addition was found to depend on the test temperature. At 25°C, thiosulphate activated the alloy dissolution rate and the higher were the thiosulphate concentrations, the higher was the corrosion rate. At 50 or 80°C, however, thiosulphate promoted the dissolution rate at early stages, but seemed to interfere with the surface film formation later on, producing a black film that effectively decreased the alloy corrosion rate. At higher potentials, however, the film became non‐protective, leading to accelerated corrosion once again.

This paper explains the corrosion behaviour of 90‐10 cupronickel alloys in seawater as a function of test temperature and thiosulphate additions.

The purpose of this paper is to study the inhibition of carbon steel corrosion under wet/dry conditions using electrochemical techniques.

Sodium dihydrogen orthophosphate, dicyclohexylamine nitrite and sodium benzoate were used as inhibitors in the investigation. Plain carbon steel specimens were treated with three different inhibitors for a set period of time. One group of the specimens was subjected to 60 wet/dry cycles whilst a second group was kept continuously immersed in distilled water during the same period. The corrosion rates of the specimens were determined by electrochemical methods at several intervals during corrosion.

The three inhibitors showed good performance during the whole 60 days of wet/dry cycling. Sodium dihydrogen orthophosphate was the best of the three, giving the lowest corrosion rates. However, during full immersion tests in distilled water, specimens that had been treated with dicyclohexylamine nitrite and sodium benzoate performed better than did those treated with sodium dihydrogen orthophosphate. Moreover, the corrosion rates were significantly higher in the case of wet/dry cycling due to differential aeration created through partial immersion, which was a consequence of the wet and dry cycling process.

This study showed the beneficial effect of inhibitors in slowing down the corrosion of steel. Furthermore, wet/dry cycling of steel samples in the laboratory produced corrosion rates that were comparable to those measured under actual outdoor conditions.

This paper aims to study the effect of flow rate (0.42∼2.09 m/s) on the corrosion behavior of WB36CN1 steel pipe in the simulated secondary circuit water environment (170°C, 6 mg/L ethanolamine + 100 µg/L NaCl), for which an autoclave was used to simulate the secondary circuit environment for carrying out related experiments.

The corrosion behaviors were studied by electrochemical methods, morphological observations and elemental analysis.

As flow rate increases, the amplitude of the current noise fluctuates increased, noise resistance R_n and spectral noise resistance R_sn decreased, the shear stress on the surface of WB36CN1 steel increases, the oxygen content on the surface decreases, the roughness becomes smaller. Meanwhile, the energy of energy distribution plot is concentrated at high frequencies under the three flow conditions, the slopes of current power spectral density curve approach 0 db/decade. This means that the oxide on the surface becomes less and corrosion rate increases with increasing flow rate. The corrosion type of WB36CN1 steel was uniform corrosion; the degree of uniform corrosion is higher at high flow rate.

The effect of flow rate on the corrosion behavior of WB36CN1 steel pipe in the secondary circuit water environment was studied by using electrochemical methods in the laboratory. The effect mechanism of flow rate for corrosion behavior was obtained.

The purpose of this paper was to investigate the corrosion behavior of X65 steel in the CO₂/oil/water environment using mass loss method, potentiodynamic polarization technique and characterization of the corroded surface techniques.

The weight loss analysis, electrochemical study and surface investigation were carried out on X65 steel that had been immersed in the CO₂/oil/water corrosive medium to understand the corrosion behavior of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of flow velocity, CO₂ partial pressure and water cut on the CO₂ corrosion rate of X65 steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature of 60°C and CO₂ partial pressure of 1 atm by recording open circuit potential/time and potentiodynamic polarization characteristics. The surface and cross-sectional morphologies of corrosion product scales were characterized using scanning electron microscopy. The phases of corrosion product scales were investigated using X-ray diffraction.

The results showed that corrosion rates of X65 steel both increased at first and then decreased with the increase of flow velocity and CO₂ partial pressure, and there were critical velocity and critical pressure in the simulated corrosive environment, below the critical value, the corrosion products formed on the steel surface were loose, porous and unstable, higher than the critical value, the corrosion product ?lms were dense, strong adhesion, and had a certain protective effect. Meanwhile, when the flow velocity exceeded the critical value, oil film could be adsorbed on the steel surface more evenly, corrosion reaction active points were reduced and the steel matrix was protected from being corroded and crude oil played a role of inhibitor, thus it influenced the corrosion rate. Above the critical CO₂ partial pressure, the solubility of CO₂ in crude oil increased, the viscosity of crude oil decreased and its fluidity became better, so that the probability of oil film adsorption increased, these factors led to the corrosion inhibition of X65 steel reinforced. The corrosion characteristics of gathering pipeline steel in the corrosive environment containing CO₂ would change due to the presence of crude oil.

The results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO₂/oil/water corrosive environment.

With the transition from supplying ships with direct current to alternating current, plus the increase in the number of electricity consumers within the coastline region, as well as with the construction of steel quays and docks and reinforced steel quays, the conditions have been created for the occurrence of wandering exchange currents in the sea. Corrosion due to these currents considerably exceeds all expectations. In this work, the rate of steel corrosion in synthetic sea‐water has been investigated in an alternating electric field. Electro‐chemical parameter measurements determining corrosion rate were performed on samples in sea‐water in an alternating current field and compared with the sample — applying a “blind test” — without an electric field. All measurements were performed at an electrolyte temperature of 20°C. Corrosion rate was investigated in dependence on the current density. The following factors were applied as measures of corrosion rate: specific concentration of Fe ions in the electrolyte and the change of potential of the steel electrode polarized within alternating electric field. Measurement results shown that in the sea‐water with an alternating electric field an increase in the corrosion of steel takes place, exceeding expected amounts. The change of steel potential in alternating current field is proportional to the corrosion rate and can be very simply applied for estimation of corrosion rate due to alternating currents.

A significant part of Finnish concrete building stock is relatively young. Thus methods to adopt the existing building stock to climate change are needed. To plan and correctly timing the service actions there is a need to study the rates of different deterioration mechanisms. The reinforcement corrosion in Finnish outdoor exposed concrete structures is almost solely carbonation-induced corrosion. In former studies, it has been shown that active corrosion phase can also have a major effect on the total service life of the structure. The paper aims to discuss these issues.

In this study, the effect of climate change on predicted corrosion rate of concrete reinforcement in projected 2050 and 2100 climates compared to present climate were studied to consider adaptation methods for the climate change. The calculations are based on a corrosion propagation model, which takes into account four different climatic factors: wind-driven rain, temperature, relative humidity and solar radiation.

A significantly higher corrosion rates and thus faster corrosion-induced damage can be expected in the future climate. The increase in corrosion rate is the highest in the late autumn and winter because of the increasing amount of precipitation and weaker conditions for concrete structures to dry. In addition, the duration of high corrosion rate periods is increasing which may shorten the propagation phase. However, corrosion rate is highly dependent on the direction of the greatest climate load and the grade of sheltering which can be taken into account in service life calculations and while planning service actions.

There are different sources of error because of the uncertainties with both the used model and the climate change scenarios. That is why the results are discussed in more general way than comparing the actual numbers with each other.

The propagation model used in this study has not been used before in adaptation studies. The climate change effect on carbonation-induced corrosion has also been limited while the studies have focused on chloride-induced corrosion.