Corrosion Of X70 Steel Research Articles

Study of the Initial Corrosion of X80 Steel in a Saturated Saline Soil Co-Contaminated with Cl-, SO42-and HCO3-

Study of the Initial Corrosion of X80 Steel in a Saturated Saline Soil Co-Contaminated with Cl-, SO42-and HCO3-

Electrochemical and surface analyses of X70 steel corrosion in simulated acid pickling medium: Effect of poly (N-vinyl imidazole) grafted carboxymethyl chitosan additive

In this work, water-soluble poly (N-vinyl imidazole) grafted carboxymethyl chitosan composite (CMCh-g-PVI) has been synthesized from chitosan, characterized and deployed as a corrosion inhibitor for API X70 in 1 M HCl. CMCh-g-PVI composite significantly reduced the corrosion of X70 steel when compared with equimolar concentration of chitosan and carboxymethyl chitosan in the same medium due to the formation of stable protective polymeric films on the metal surface. This was confirmed by means of scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. In depth electrochemical corrosion study was conducted after chloride treatment using potentiodynamic polarization and electrochemical impedance spectroscopic techniques on precleaned substrates. This polymer composite may have a future as an efficient ingredient in corrosion inhibitor formulations for metal surface treatments.

The synergistic corrosion inhibition study of different chain lengths ionic liquids as green inhibitors for X70 steel in acidic medium

For this study, three corrosion inhibitors with different anionic carbon chain lengths, 1-vinyl-3-methylimidazolium iodide ([VMIM]I), 1-vinyl-3-proplylimidazolium iodide ([VPIM]I) and 1-vinyl-3-butylimidazolium iodide ([VBIM]I) were studied on the corrosion of X70 steel in 0.5 M H2SO4 solution at 298 K by electrochemical measurements, weight loss methods, scanning electron microscope (SEM), FTIR spectra, atomic force microscopy (AFM) and theoretical calculation. Three inhibitors with synergistic effect of iodide ions are mixed-type inhibitors with excellent inhibition efficiency. The order of corrosion inhibition efficiency is: [VMIM]I < [VPIM]I < [VBIM]I according to theoretical and experimental study, indicating the inhibition performance was improved with the increase of alkyl chain length attached to imidazolium ring, owing to its electron-donating effect of alkyl groups. The adsorption of three inhibitors including physisorption and chemisorption obeyed Langmuir adsorption isotherm.

Effect of residual and external stress on corrosion behaviour of X80 pipeline steel in sulphate-reducing bacteria environment

Abstract X80 pipeline steel has a wide application prospect. This steel is easily affected by sulphate-reducing bacteria (SRB) in neutral soil and causes stress-corrosion cracking. Based on the results of static and dynamic electrochemical tests, the corrosion behaviour and mechanism of X80 pipeline steel under the synergistic effect of stress and SRB in Shenyang soil environment were investigated through slow strain rate testing, electrochemical impedance spectroscopy, potentiodynamic polarisation technique and surface analysis techniques. Results showed that internal residual and external tensile stress accelerate the corrosion of X80 steel, and the effect of SRB is influenced by the stress type. When only residual stress is applied, the SRB adsorption film plays a certain protective role, which reduces the corrosion sensitivity of X80 steel, and its corrosion mechanism is the anode dissolution of the film rupture. When tensile stress is applied, stress and SRB play a role in the stress concentration at the crack tip, thereby increasing the corrosion sensitivity of X80 steel. The corrosion mechanism is then the activated anode dissolution.

Effect of flow rate on localized corrosion of X70 steel in supercritical CO2 environments

The effect of flow rate on localized corrosion of X70 steel in supercritical CO2-saturated aqueous phase was studied. Results shown that flow rate changed the predominant type from general corrosion (static condition) to localized corrosion (dynamic condition), and the localized corrosion rate gradually increased with time under dynamic condition. The main localized corrosion type initiated at the early corrosion stage the local spalling amorphous layer transformed to FeCO3 scale, and localized corrosion could also occur due to the broken of dense FeCO3 scale. The critical diameter of the pit for FeCO3 scale growth inside it decreased exponentially with flow rate.

Electrochemical behavior and localized corrosion of X65 steel in high salt concentration brines with CO2 saturated

The electrochemical characteristics and localized corrosion of X65 steel were investigated in CO2-saturated brines as a function of salt concentration employing electrochemical techniques and immersion tests. The results show that, as salt concentration increases, the corrosion mechanism changes from electrochemical steps control to the mixed control of mass transfer and electrochemical steps. The higher the salt concentration is, the more obvious the mass transfer control will be. The corrosion rate firstly increases and then decreases with salt content. There is a maximum corrosion rate somewhere between 60 and 120 g l−1 salt content. The salting-out effect may play a crucial role in steel corrosion in CO2-bearing systems with higher salt concentrations. Chloride ions account for the decrease of the surface layer thickness and make them non-adherent, thereby promoting the initiation and development of localized corrosion at salt concentration above 120 g l−1.

Corrosion effect of Bacillus cereus on X80 pipeline steel in a Beijing soil environment

The corrosion of X80 pipeline steel in the presence of Bacillus cereus (B. cereus) was studied through electrochemical and surface analyses and live/dead staining. Scanning electron microscopy and live/dead straining results showed that a number of B. cereus adhered to the X80 steel. Electrochemical impedance spectroscopy showed that B. cereus could accelerate the corrosion of X80 steel. In addition, surface morphology observations indicated that B. cereus could accelerate pitting corrosion in X80 steel. The depth of the largest pits due to B. cereus was approximately 11.23μm. Many pits were found on the U-shaped bents and cracks formed under stress after 60days of immersion in the presence of B. cereus. These indicate that pitting corrosion can be accelerated by B. cereus. X-ray photoelectron spectroscopy results revealed that NH4+ existed on the surface of X80 steel. B. cereus is a type of nitrate-reducing bacteria and hence the corrosion mechanism of B. cereus may involve nitrate reduction on the X80 steel.

Corrosion Behavior of API 5L X80 Steel in the Produced Water of Onshore Oil Recovery Facilities

High-strength low-alloy steel is used in pipelines, which transport oil/gas and also produced water in the process of the secondary recovery of oil. This paper investigates the corrosion of X80 steel after immersion in static systems (biotic and abiotic). The corrosion rate, the corrosion morphology and the hardness of the coupons were investigated. The corrosion products were determined by SEM/EDS and XRD. The corrosion rates of the coupons in the biotic system were moderate and had an agressive pit morphology, while those of the coupons in the abiotic system were low with less aggressive pit. The hardness of the coupons after exposure to the systems of produced water was not changed compared with that of the control coupons. The corrosion products formed in the biotic system were Fe(OH)3, Fe(OH)2, FeOOH, Fe3O4, FeS2, FeCl3, and in the abiotic system, NaCl, CaCl2 and SrSO4. BaSO4 and CaCO3 were identified in both systems.

Effect of interfacial film on the corrosion behaviour of X80 pipeline steel in a neutral soil environment containing sulphate-reducing bacteria

AbstractX80 pipeline steel is inevitably corroded by sulphate-reducing bacteria (SRB) in soil. Corrosion-induced damage to the pipeline steel could result in serious consequences. Studies have shown the critical role of interfacial film in SRB-induced corrosion. However, the specific effect of interfacial film was not examined. The effect of film on the corrosion of X80 steel in neutral soil environment was determined using scanning electron microscopy, energy-dispersive spectroscopy, and electrochemical impedance spectroscopy. The structure and electrochemical characteristics of the surface film of X80 steel were examined in the presence of SRB in Shenyang soil. The results showed that, at the beginning of immersion (14 h), the steel surface mainly adsorbed the SRB biofilm, and the biofilm slowed down the corrosion reaction. A small amount of the biofilm and corrosion product film was observed on the electrode surface after immersion for 14–48 h. The corrosion product film destroyed the protection of the biofilm, increasing corrosion. After immersion for 48 h, the corrosion product contents and polarisation resistance increased. After immersion for 240 h, a dense corrosion product film formed on the sample surface, showing the least corrosion. The protective effect of corrosion products on X80 steel was much greater than that of the biofilm.

Inhibition of X80 steel corrosion in oilfield acidizing environment using 3-(2-chloro-5,6-dihydrobenzo[b][1]benzazepin-11-yl)-N,N-dimethylpropan-1-amine and its blends

Corrosion of X80 steel was investigated in simulated acidizing fluids containing different concentrations of 3-(2-chloro-5,6-dihydrobenzo[b][1]benzazepin-11-yl)-N,N-dimethylpropan-1-amine (3CDA) at different temperatures using weight loss and electrochemical techniques. X80 steel used corroded at higher rates in the uninhibited acid solution than in the inhibited solutions. Inhibition efficiency of 3CDA was highest (88.8%) at 10×10−5M concentration at 30°C and decreased as temperature decreased. Some intensifiers were added to improve the inhibition efficiency at high temperatures. The 3CDA acts as mixed type inhibitor and adsorbs spontaneously on steel surface by physical and chemical interactive forces. Techniques such as FTIR, SEM and EDAX were also employed to characterize the potential of 3CDA as efficient steel corrosion inhibitor for oilfield application.

Enhanced surface protective performance of chitosanic hydrogel via nano-CeO2 dispersion for API 5L X70 alloy: Experimental and theoretical investigations of the role of CeO2

In situ CeO2 pigment dispersion in chitosanic hydrogel suspension has contributed to the reduction of API 5L X70 steel corrosion in acidified NaCl. We have conducted in-depth studies on the contributions of CeO2 with regards to the protective performance of this organic-inorganic hybrid conjugate by corrosion electrochemistry and surface analytical techniques. Increment in CeO2 content predominantly affected cathodic hydrogen evolution. It also led to significantly reduced magnitudes of corrosion current density as insulating layers of protective hybrid inhibitor films were formed on steel, compared to CHS alone. The effect of CeO2 and its contributions towards enhanced surface barrier performance have been established by experimental/theoretical studies.

Effect of main controlling factor on the corrosion behaviour of API X65 pipeline steel in the CO2/oil/water environment

PurposeThe purpose of this paper was to investigate the corrosion behaviour of API X65 pipeline steel in the simulated CO2/oil/water emulsion using weight loss technique, potentiodynamic polarization technique and characterization of the corroded surface techniques.Design/methodology/approachThe weight loss analysis, electrochemical study and surface investigation were carried out on API X65 pipeline steel that had been immersed in the CO2/oil/water corrosive medium to understand the corrosion behaviour of gathering pipeline steel. The weight loss tests were carried out in a 3L autoclave, and effects of temperature, CO2 partial pressure, water cut and flow velocity on the CO2 corrosion rate of API X65 pipeline steel were studied. Electrochemical studies were carried out in a three-electrode electrochemical cell with the test temperature was 60°C, and the CO2 partial pressure was 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.FindingsThe results showed that water cut was the main controlling factor of API X65 steel corrosion under the conditions of CO2/oil/water multiphase flow, and it had significant impact on corrosion morphology. In the case of higher water cut or pure water phase, general corrosion occurred on the steel surface. While water cut was below 70 per cent, corrosion morphology transformed into localized corrosion, crude oil decreased corrosion rate significantly and played a role of inhibitor. Crude oil hindered the corrosion scales from being dissolved by corrosive medium and changed dimension and accumulation pattern of the crystal grain, thickness and structure of the corrosion scales; thus, it influenced the corrosion rate. The primary corrosion product of API X65 steel was ferrous carbonate, which could act as a protective film at low water cut so that the corrosion rate can be reduced.Originality/valueThe results can be helpful in selecting the suitable corrosion inhibitors and targeted anti-corrosion measures for CO2/oil/water corrosive environment.

Ceria/Acrylic Polymer Microgel Composite: Synthesis, Characterization, and Anticorrosion Application for API 5L X70 Substrate in Chloride-Enriched Medium

Ceria/poly(acrylic acid) microgel composite with anticorrosion potential has been synthesized via an in situ polymerization method. This polymer composite matrix has demonstrated significant reduction in API 5L X70 steel corrosion in 0.5 M HCl. In-depth studies of the anticorrosion properties of this microgel have been conducted by corrosion electrochemistry, and its adsorption on steel altered both anodic dissolution and cathodic hydrogen evolution in the acid medium. Increment of CeO2 content within the PAA/CeO2 hybrid composite improved its surface protective performance; 1 and 5 g of CeO2 within the composite recorded 82 and 90% inhibition efficiency, respectively, compared to PAA alone (62%), at equal concentration. PAA formed a protective polymeric film on steel upon molecular adsorption, but in the presence of the PAA/CeO2, the metal surface protection was enhanced by the adhesion of compact hybrid films. PAA/CeO2 microgel composite may have a future as an anticorrosive paint component for metal su...

The effects of thioureido imidazoline and NaNO2 on passivation and pitting corrosion of X70 steel in acidic NaCl solution

The effects of thioureido imidazoline and NaNO2 on passivation and pitting corrosion of X70 steel in acidic NaCl solution were studied. The addition of thioureido imidazoline promoted passivation of the steel in the NaCl-NaNO2 solution, but the pitting potential decreased, which was attributed to the preferential adsorption of residue thiourea monomers in the inhibitor. With longer immersion time, the pitting potential in solution with thioureido imidazoline+NaNO2 increased to the value with only NaNO2. A multi-layer film formed with thiourea rich in inner and imidazoline rich in outer. The compounded inhibition effect of thioureido imidazoline and NaNO2 was discussed.

Cathodic Reactions Involved in the Corrosion of X80 steel in Acidic Soil Simulated Solution

Cathodic Reactions Involved in the Corrosion of X80 steel in Acidic Soil Simulated Solution

A Novel Emulsion Flow Loop for Investigating the Corrosion of X65 Steel in Emulsions with H2S/CO2

Corrosion resistance (RP) of X65 steel was investigated in an oil-in-water emulsion containing H2S and CO2 at several oil concentrations and different flow regions using a novel emulsion flow loop. One working electrode was mounted in the flow developing region while the other one was mounted in a region where the flow is fully developed. The experimental results show that the addition of CO2 to an H2S containing emulsion decreases the corrosion rate. The RP in the flow developing region is less than that in the fully developed region and it increases with increasing oil concentration. This flow loop is a promising tool for investigating the RP of engineering materials in a simulated environment similar to that encountered in the petroleum industry.

Effect of impurity on the corrosion behavior of X65 steel in water-saturated supercritical CO2 system

A range of impurities from various CO2 capture processes may exist in supercritical CO2 transport pipeline in carbon capture and storage process. In this regard, the corrosion behavior of X65 steel in water-saturated supercritical CO2 containing O2, H2S, SO2 or NO2 impurity was investigated using weight loss measurement and surface characterization. The corrosion impact factor was defined which showed that NO2 or SO2 had the greatest influence on the corrosion of X65 steel, followed by H2S and O2. Localized corrosion occurred in water-saturated supercritical CO2 system containing NO2 with or without other impurities. Low concentrations of impurities could notably change the corrosion rate and the characteristics of corrosion scale via changing the corrosion mechanism, and thus the corrosion effect of CO2 weakened in water-saturated supercritical CO2 system containing impurities.

Effects of laser surface melting on erosion–corrosion of X65 steel in liquid–solid jet impingement conditions

Laser surface melting (LSM) has the potential to increase the resistance of steels to erosion–corrosion. In this study a submerged jet impingement system containing a brine under saturated CO2 conditions with sand has been used to assess the effect of LSM on the erosion–corrosion resistance of X65 steel. Erosion–corrosion rates under different experimental conditions were deduced based on CFD-simulated results and surface profile measurements. Scanning electron microscopy (SEM) was used to observe the morphology of erosion–corrosion damage. The results show that the erosion–corrosion rates at various impact angles can be decreased by LSM. Changes in microstructure, corrosion behavior and hardness of X65 steel induced by laser treatment were analyzed by using optical microscopy, transmission electron microscopy (TEM), energy dispersive X−ray (EDX) analysis together with electrochemical polarization and hardness distribution measurements, in order to clarify how laser treatment imparts the effects on the steel.

Effect of the Size of Soil Particles on the Electrochemical Corrosion Behavior of Pipeline Steel in Saline Solutions

By using a standard quartz replace of sandy soil particles, we investigate the effect of size of soil particles (0.1–0.25 mm, 0.6–1.0 mm) on the electrochemical corrosion behavior of X70 pipeline steel in sandy-soil corrosive environment simulated by 3.5 wt.% sodium chloride (NaCl) with the help of the polarization curve and electrochemical impedance spectroscopy (EIS) technology. The results indicate that the polarization resistance of X70 steel decreases as the particle size decreases. For all polarization curves, a right shift of the cathodic branch with decreasing particle sizes is observed. The corrosion of X70 steel is controlled by the cathode process of diffusion and oxygen reduction at the metalenvironment interface, the intensity of which increases as the particle size decreases.

Synergistic effect of O2, H2S and SO2 impurities on the corrosion behavior of X65 steel in water-saturated supercritical CO2 system

The synergistic effect of O2, H2S and SO2 impurities on the corrosion behavior of X65 steel corrosion was evaluated in the water-saturated supercritical CO2 system. Weight loss measurements showed that the synergistic effect of multiple impurities significantly increased the corrosion rate of steel. Surface characterization of corrosion scales using SEM, EDS and XRD showed that low concentrations of impurities notably changed the characteristics of corrosion scales. The interactions among O2, H2S and SO2 resulted in additional formation reactions of elemental sulfur, sulfuric acid and water and consequently accelerated the corrosion of steel consistent with the high synergistic interaction impact factors.