Steel In H2S Research Articles

Insights into the newly synthesized bi- Mannich base for carbon steel corrosion inhibition in H2S and HCl solution

Adding corrosion inhibitors is considered to be a cost-effective way to inhibit metal corrosion. In this study, we report the synthesis of a bi-mannich base corrosion inhibitor (BMT) with an impressive inhibition efficiency on carbon steel in H2S and HCl co-existing solution. At the BMT concentration of 9 ppm, the inhibition efficiency (η) of 96.9%, 97.6% and 98.0% were determined by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy, respectively. The adsorption of BMT on the carbon steel surface follows the Langmuir adsorption isotherm, and the calculated free energy indicates that the adsorption is a spontaneous process. This research also delves into understanding the adsorption behavior and corrosion inhibition mechanism of BMT on carbon steel surfaces through quantum chemistry calculations. The results of this study provide guidance for the application of BMT as a corrosion inhibitor in sour and acid environments.

Simultaneous inhibition of natural gas hydrate formation and CO2/H2S corrosion for flow assurance inside the oil and gas pipelines

Compatibility problems are observed during the co-injection of corrosion and gas hydrate inhibitors inside oil and gas pipelines, which reduces their performance. In this study, the newly synthesized dual-purpose inhibitors (DPIs) were developed to overcome the compatibility challenge between the inhibitors. A detailed experimental and computational study was performed to investigate the inhibition activity of DPIs. The results of constant cooling experiments showed that the inhibitors significantly prevented natural gas hydrate formation. DPI2 with a propyl pendant group was the best sample by providing a subcooling temperature of 18.1 °C at 5000 ppm. DPI1 and DPI3 decreased gas consumption by 2.6 and 2.4 times, respectively, compared to pure water. In addition, molecular dynamics simulation revealed that the transportation of gas molecules to the growing hydrate cages was disrupted due to DPI2 adsorption on the surface of the hydrate, which partially covered it and acted as a mass transfer barrier. Furthermore, the interaction of the anion part of the inhibitor with the nearest neighbor water molecules lowered the water activity to form the hydrogen-bonding networks for the hydrate formation. According to corrosion measurements, DPIs suppressed the corrosion rate of mild steel in H2S–CO2 saturated oilfield-produced water, and a maximum inhibition efficiency of 96.3% was obtained by adding 1000 ppm of DPI2. Moreover, the estimated adsorption energy of DPI2 were relatively high and matched with experimental data, implying that the inhibitor has a high degree of adsorption on the metal for forming a protective layer on the mild steel surface. These findings signified that DPIs provide a potential hybrid inhibition of corrosion and gas hydrate formation for flow assurance applications and reduce the operation costs.

Hydrogen embrittlement of high-strength API carbon steels in H2S and CO2 containing environments

This study aims to understand the Sulfide Stress Cracking (SSC) resistance of API carbon steels exposed to wet sour environments containing CO2. A mini-pipe specimen was cut from API grade tubulars and placed in an SSC test cell to perform the investigation. The specimen was highly strained and internally pressurized while exposed to the corrosive environment for seven days. The partial pressure ratio (PPR) of CO2 (i.e. ratio of partial pressure of CO2 to the total pressure) was varied to study the effect of CO2 content on SSC. Experiments were performed while maintaining a constant H2S concentration and temperature. The steels' variations in mechanical properties (ultimate tensile strength and plastic strain before failure) after exposure to the sour environment are used to quantify the embrittlement. In addition, the specimens were examined using optical microscopes to assess the severity of the SSC corrosion based on shear deformation patterns and crack features. The SSC resistance of the tested steels was minimized when the PPR of CO2 was approximately 20%. Results demonstrate that the materials have adequate SSC corrosion resistance to be utilized in the environment containing 280 ppm H2S. Nevertheless, their SSC resistance reduced noticeably between 10 and 30% PPR of CO2.

Combined effect of hydrogen embrittlement and corrosion on the cracking behaviour of C110 low alloy steel in O2-contaminated H2S environment

The cracking behavior of sulfide stress cracking resistant C110 steel in O2-contaminated H2S environment was investigated by cracking and corrosion simulation tests. With the increase of O2 partial pressure, the cracking susceptibility and corrosion rate of C110 steel significantly increased. The O2 ingress affects the whole cracking behaviour involving a multi-stage process: the oxidation reactions of H2S, the corrosion reactions on the metal surface and the degradation and cracking of martensitic multiscale boundaries. The cracking mechanism of C110 steel in H2S and O2-containing environment is attributed to the combined effect of hydrogen embrittlement and anodic dissolution.

Sensitivity to hydrogen induced cracking, and corrosion performance of an API X65 pipeline steel in H2S containing environment: influence of heat treatment and its subsequent microstructural changes

In this investigation, the effect of microstructural changes and phase equilibria on corrosion behavior and hydrogen induced cracking (HIC) sensitivity of an API X65 pipeline steel was studied. For this purpose, heat treatment was performed at 850 °C, 950 °C, 1050 °C and 1150 °C to engineer the desired microstructure of this pipeline steel. Then, the microstructural evolution was performed by optical microscopy, and Field Emission Scanning Electron Microscopy (FE-SEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS). Corrosion properties were evaluated in H2S environment by open circuit potential (OCP), Potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS). As well, HIC sensitivity of the API X65 pipeline steel was assessed by hydrogen charging of the cathode and immediately conducting the tensile test. Microscopy analyses showed that the microstructure of the steel is ferritic-pearlitic together with the islands of martensite/austenite constituents. Increasing the heat treatment temperature reduced the amount of pearlite and increased ferrite grain size. It also stabilized the ferrite content. Corrosion results indicated that no active layer was formed on the surface of this pipeline steel. Also, increasing the heat treatment temperature increased the corrosion resistance and reduced sensitivity to micro-galvanic localized corrosion. As well, results suggested that the sensitivity to HIC in the API X65 pipeline was substantially increased with increasing the amount of pearlite and reducing the amount of ferrite; i.e. at lower heat treatment temperature.

Inhibiting Effect of Ionic Liquids on the Corrosion of Mild Steel in H2S and HCl Solution

AbstractFour imidazolium‐based ionic liquids (ILs) were selected to investigate the inhibiting effect of ILs with various alkyl chain lengths on the corrosion of mild steel in H2S and HCl solution using electrochemical experiments, weight loss and surface analyses, and quantum chemical study. The results demonstrated that these ILs acted as mixed‐type inhibitors and efficiently inhibited the corrosion of mild steel in H2S and HCl solution. Their excellent corrosion inhibition ability was due to their adsorption process on the metal surface, which followed the Langmuir adsorption isotherm. Furthermore, extending the alkyl chain length in the ILs could improve their inhibition performance.

Experimental and theoretical studies of five imidazolium-based ionic liquids as corrosion inhibitors for mild steel in H2S and HCl solutions

In this study, the mild steel corrosion inhibition performance and the corresponding mechanisms of five imidazolium-based ionic liquids (ILs) in hydrogen sulfide (H2S) and hydrochloric acid (HCl) solutions were investigated using electrochemical experiments, weight loss measurement, morphology analysis, and quantum chemical calculation. The results revealed that these ILs inhibited the corrosion of mild steel in H2S and HCl solutions and did not change the corresponding mechanism of the corrosion reaction. The corrosion inhibition ability of these ILs decreased when the temperature increased. 1-Allyl-3-methylimidazolium bromide ([Amim]Br) exhibited the strongest mild steel corrosion inhibition capacity in H2S and HCl solutions. The corrosion inhibition capacity of the ILs can be attributed to their adsorption on metal surfaces, which obeys the Langmuir adsorption isotherm. E HOMO exhibited a higher influence than E LUMO on the corrosion inhibition performance of the imidazolium-based ILs.

Localized Corrosion of Mild Steel in H2S Containing Aqueous Environments—Case Studies and Common Mechanisms

The current study is aimed at proposing a common mechanism of localized corrosion of mild steel in H2S containing aqueous environments, by utilizing experimental findings reported in a number of st...

Synergistic inhibition effects of octadecylamine and tetradecyl trimethyl ammonium bromide on carbon steel corrosion in the H2S and CO2 brine solution

The corrosion inhibition performances of octadecylamine (OCT) and tetradecyl trimethyl ammonium bromide (TTAB) for carbon steels in H2S and CO2 brine solution were investigated by weight loss, potentiodynamic polarization, molecular dynamic simulation and XPS analysis. TTAB showed better inhibition effects on H2S and CO2 induced corrosion than OCT. Synergistic corrosion inhibition effect was found between OCT and TTAB with proper mass ratios and the best inhibition performance was achieved with 10mgL−1 OCT and 20mgL −1 TTAB. The synergism was correlative to the fractional free volume of the inhibitor film of OCT and TTAB.

Corrosion inhibition of SAE 1018 carbon steel in H2S and HCl solutions by lemon verbena leaves extract

Abstract H2S and HCl can be noted among the most important corrosive factors existing in different parts of the oil industry. This study was performed to investigate the corrosion taking place in those parts of oil industry which simultaneous presence of both HCl and H2S are considered. The corrosion inhibition behavior of lemon verbena leaves extract on carbon steel in H2S and HCl solutions was studied by means of methods such as, Tafel polarization and electrochemical impedance spectroscopy (EIS). Tafel polarization plots showed that the lemon verbena extract acts as a mixed-type inhibitor. The adsorption mechanism was found physisorption. Δ G ads 0 and k ads were determined and discussed and Langmuir isotherm was selected as the best fitted adsorption isotherm. According to the obtained results, the maximum value of inhibition efficiency was obtained about 95.61% in the presence of 2.7 g/L, lemon verbena extract.

Synergistic corrosion inhibition effect of quinoline quaternary ammonium salt and Gemini surfactant in H2S and CO2 saturated brine solution

Corrosion inhibition of a quinolinium quaternary ammonium salt and a Gemini surfactant, 1,3-bis(dodecyldimethylammonium chloride)-2-propanol, for mild steel in H2S and CO2 saturated brine solution was investigated by using polarization test, EIS and XPS. The synergistic effect is found between these two compounds when the Gemini concentration is less than 50mgL−1 in the solution containing 100mgL−1 quinolinium quaternary ammonium salt, and it disappears when the Gemini concentration is larger than 50mgL−1. The synergistic mechanism is explained by competitive adsorption of these two compounds on steel surface.

Role of alloyed copper on corrosion resistance of austenitic stainless steel in H2S–Cl− environment

Corrosion test, surface analysis and thermodynamic calculation were carried out in the H2S–Cl− environments to clarify the role of alloyed Cu on the corrosion resistance of austenitic alloys. The alloyed Cu improved pitting corrosion resistance in the H2S–Cl− environment. The surface film of Cu-containing alloy indicated double layer consists of copper sulfide and chromium oxide, and the copper sulfide was able to exist stably compared to iron sulfide and nickel sulfide. It is concluded that the copper sulfide would enhance the formation of chromium oxide film which improve the pitting corrosion resistance in the H2S–Cl− environment.

Stress corrosion cracking of 2205 duplex stainless steel in H2S–CO2 environment

Stress corrosion cracking (SCC) behavior of 2205 duplex stainless steel (DSS) in H2S–CO2 environment was investigated by electrochemical measurements, slow strain rate test (SSRT), and scanning electron microscopy (SEM) characterization. Results demonstrated that the passive current density of steel increases with the decrease of solution pH and the presence of CO2. When solutions pH was 2.7, the steel SCC in the absence and presence of CO2 is expected to be a hydrogen-based process, i.e., hydrogen-induced cracking (HIC) dominates the SCC of the steel. The presence of CO2 in solution does not affect the fracture mechanism. However, the SCC susceptibility is enhanced when the solution is saturated simultaneously with H2S and CO2. With elevation of solution pH to 4.5, the hydrogen evolution is inhibited, and dissolution is involved in cracking process. Even in the presence of CO2, the additional cathodic reduction of H2CO3 would enhance the anodic reaction rate. Therefore, in addition to the hydrogen effect, anodic dissolution plays an important role in SCC of duplex stainless steel at solution pH of 4.5.

Automation of a McBain-Bakr-type thermogravimetric analyzer using a digital image correlation technique

Thermogravimetric analysis was used to obtain corrosion kinetics data for several materials in high-temperature environments. A thermogravimetric analyzer has been developed that uses a McBain-Bakr quartz spring balance in conjunction with a digital image acquisition and analysis package to accurately characterize materials through image correlation. This provides a new method for automatically measuring mass changes continuously with a variable resolution depending on the spring component. The decomposition of calcium oxalate was used to verify the validity of the technique. The results show two reactions, whose reaction temperatures were determined by the intercept method, upon heating to 650 °C. The mass loss at the first reaction temperature, 200 °C, was 20% and a 30% loss was observed at 500 °C. Comparison of the experimentally obtained results with those of other researchers who used commercial instruments suggests that the method of using digital image analysis in conjunction with a spring to monitor mass change is a viable and accurate replacement for automatic electrobalances and cathetometers for thermal analysis of materials. Additional comparison between corrosion tests performed on SA210 steel in H2S using both a commercial thermobalance and the developed technique confirmed that high-temperature corrosion can be monitored accurately with the proposed method.