Role of polyacrylamide concentration on corrosion behavior of N80 steel in the HPAM/H2S/CO2 environment

The effect of polyacrylamide on corrosion behavior of N80 steel in the HPAM/H₂S/CO₂ environment was studied by using weight-loss and electrochemical tests to simulate the environment of production wells in polymer flooding. The morphology and composition of corrosion scales were studied by scanning electron microscopy, energy dispersive X-ray spectrometer, and X-ray photoelectron spectroscopy. The results show that as the polyacrylamide concentration increases, the uniform corrosion rate of N80 steel decreases gradually. The safe service life of N80 steel grows along with the increase of the concentration of polyacrylamide. The corrosion scales of N80 steel in the HPAM/H₂S/CO₂ environment is split into two layers, an inner layer of O-rich composed of FeCO₃ and an outer layer of S-rich consisting of FeS. Polyacrylamide adsorbs on the surface of N80 steel to form a protective network, which blocks contact between the metal and the solution and then inhibits the anodic dissolution of the metal. Moreover, the growth of polyacrylamide concentration increases the pH value of the solution and promotes the ionization of H₂S, HS⁻, and H₂CO₃ in the solution.     

Electrochemical and Sulfide Stress Corrosion Cracking Behaviors of Tubing Steels in a H2S/CO2 Annular Environment

The electrochemical and sulfide stress corrosion cracking (SSCC) behaviors of 13Cr stainless steel and P110 steel were investigated in a simulated acidic annular environment with low-temperature and high-pressure H₂S/CO₂ using electrochemical methods, U-bend immersion tests, and scanning electron microscopy. In the solution containing high pressure CO₂, 13Cr, and P110 steels exhibited general corrosion and severe pitting, respectively. Compared with sweet corrosion, additional H₂S in the solution enhanced the corrosion of 13Cr steel but inhibited the corrosion of P110 steel. By contrast, in a solution containing 4 MPa CO₂ and different $ {P}_{{{\text{H}}_{ 2} {\text{S}}}}$ (0-0.3 MPa), the susceptibility of both 13Cr stainless steel and P110 steel toward SSCC was significantly promoted by increases in H₂S partial pressure. The 13Cr stainless steel exhibited higher susceptibility toward SSCC than P110 steel under a H₂S/CO₂ environment but lower susceptibility under a pure CO₂ environment.     

CO2对H2S／CO2环境中P110钢应力腐蚀的影响研究

采用恒载荷拉伸法、腐蚀电化学测试和断口分析技术等,研究了P110钢在不同H2S／CO2含量的NACE-A溶液中的硫化物应力腐蚀（SSCC）行为．结果表明,在加载初期,P110钢的自腐蚀电位Ecorr）急剧下降,至极小值后缓慢升高,达到稳定值后直至断裂,试样断口呈脆性解理状．当通入CO2量达到17％时,P110钢的自腐蚀...     

Comparison of corrosion scales formed on KO8OSS and N8O steels in CO2/H2S environment

Abstract

Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were applied to analyse the microstructure and composition of the corrosion scale formed on KO80SS and N80 tubes with carbon dioxide (CO₂) and hydrogen sulphide (SO₂). The corrosion scales of both KO80SS and N80 tubes were of the double layer structure, and not only uniform corrosion but also localised corrosion was observed. The crystal of the surface layer is laminar. The main phase in the outer layer is calcium carbonate (CaCO₃), and the inner scale consisted of iron carbonate (FeCO₃) for KO80SS steel and FeS_0·9 with a little amount of FeCO₃ for N80 steel respectively. Additionally, the electrochemical techniques were used to investigate the characteristics of the corrosion scales. The results indicated that the polarisation resistance R_p of KO80SS steel film was nobler than that of N80 steel film. Finally, the corrosion current I_corr of KO80SS steels was lower than that of N80 steels. Corrosion scale of KO80SS tube steels is more protective to the matrix than that of N80 tube steels.     

Inhibition of mild steel corrosion in CO2 and H2S-saturated acidic media by a new polyurea-based material

Oil well acidizing is a common practice used to boost oil well productivity in the industry. This practice, however, exposes the mild steel components of the wells to extremely harsh corrosive environments. Under such conditions, highly efficient inhibitors are used to minimize corrosion attack. In the present study, corrosion inhibition of mild steel in simulated acidic medium saturated with CO₂ and H₂S gases by a newly synthesized polyurea-based material (PUCorr-1) was investigated. Electrochemical studies supported with quantum chemical density-functional theory calculations and surface characterization revealed that PUCorr-1 adsorbs onto mild steel through a chemisorption mechanism yielding a stable protective film. The polyurea exhibited an excellent efficiency of 99.9% at a temperature of 50°C and a low concentration of 100 ppm, yielding a corrosion current density of 0.3 µA/cm². In the presence of CO₂ and H₂S gases, PuCorr-1 exhibited a remarkable performance (>93% efficiency) making it a potential corrosion inhibitor in industrial processes that involve the use of acid solutions in the presence of CO₂ and H₂S gases.     

H2S 分压对 13Cr 不锈钢在 CO2注气井环空环境中应力腐蚀行为的影响简

利用高压下的电化学实验及U型弯浸泡实验结合微观分析手段,研究了13Cr不锈钢在不同H2S分压下CO2注气井环空环境模拟液中的电化学特征及应力腐蚀规律。结果表明:油套管钢的刺漏现象以及环境中硫酸盐还原菌的存在使得环空环境成为复杂的高压H2S-CO2-Cl-环境,13Cr不锈钢在该种环境下具有明显的应力腐蚀敏感性。随着H2S分压的升高,13Cr不锈钢击破电位下降,应力腐蚀敏感性增强,这主要因为H2S分压的增大对不锈钢表面膜(钝化膜及腐蚀产物膜)的破坏作用加强。当H2S分压达到0.20 MPa时,13Cr不锈钢发生明显的应力腐蚀,断口表现为由沿晶应力腐蚀裂纹(IGSCC)和穿晶应力腐蚀裂纹(TGSCC)组成的混合断口,应力腐蚀受阳极溶解和氢致开裂共同控制。     

Stress corrosion cracking behaviour of 316L stainless steel exposed to CO2–H2S–Cl− environments in the absence and presence of methyldiethanolamine (MDEA)

Stress corrosion cracking (SCC) behaviour of 316L stainless steel in CO₂–H₂S–Cl^? environments with and without methyldiethanolamine (MDEA) was investigated by slow strain rate testing and scanning electron microscopy (SEM). The results show that elongation ratio, reduction in area ratio (RAR) and time to failure ratio (TTFR) of 316L stainless steel were low in CO₂–H₂S–Cl^? environments. The corresponding fractography exhibited flat brittle fracture with quasi-cleavage pattern, indicative of high SCC susceptibility. Hydrogen penetration and corrosion pits could be responsible for the high SCC susceptibility of 316L stainless steel in this condition. For the CO₂–H₂S–Cl^? environments in the presence of MDEA, 316L stainless steel possessed high ER, RAR and TTFR (nearly 100%). High SCC resistance of 316L stainless steel could be associated with MDEA induced removal of H₂S/CO₂ and absorption on the steel surface.     

Thermal-sprayed Fe-10CM3P-7C amorphous coatings possessing excellent corrosion resistance

An alloy of Fe-10Cr-13P-7C was thermally sprayed by three different processes: (1) 80 kW low-pressure plasma spraying (LPPS), (2) high-velocity oxyfuel (HVOF) spraying, and (3) 250 kW high-energy plasma spraying (HPS). The as-sprayed coating obtained by the LPPS process was composed of an amorphous phase. In contrast, the as-sprayed coatings obtained by the HVOF and HPS processes were a mixture of amorphous and crystalline phases. The as-sprayed coatings showed a high hardness of 700 DPN. A very fine structure composed of ferrite, carbide, and phosphide was formed, producing a maximum hardness of greater than 1000 DPN in the LPPS coating just after crystallization on tempering. The corrosion re-sistance of the amorphous coating was superior to a SUS316L stainless steel coating in 1N H₂SO₄ solution and 1N HC1 solution. Furthermore, the amorphous coating underwent neither general nor pitting corro sion in1NUCI solution and 6% FeCl₃ 6H₂O solution containing 0.05N HCl, whereas the SUS316L stain less steel coating was attacked aggressively.     

Roles of carbon dioxide and steam on the hydrogen embrittlement of 3Cr tube steel in synthetic natural gas environment

The hydrogen embrittlement behaviour of 3Cr has been investigated under mixed H₂ with CO₂ at different strain rates, hydrogen partial pressures, and in the presence/absence of steam. The slow strain rate test results show that the HE susceptibility of 3Cr increased with increasing hydrogen partial pressure, and the plasticity of 3Cr obviously decreased in the presence of steam. The effect of strain rate was negligible in H₂/CO₂ environment but showed a significant difference in H₂/CO₂/steam environment. The fracture was a ductile fracture mode in N₂ environment and a brittle fracture mode in H₂/CO₂/steam environment. The reason for the severe plasticity loss of 3Cr in H₂/CO₂/steam environment was probably that the steam has a preferential adsorption onto the 3Cr surface compared with H₂ and CO₂. Consequences in CO₂ combined with H₂O to form H₂CO₃, which accelerated the anodic dissolution of 3Cr, and the physical adsorption of H₂ on steel was enhanced.     

注多元热流体环境下流速对N80钢腐蚀行为的影响研究

目的 研究不同流速条件下N80钢在注多元热流体环境中的腐蚀特征,探究流速变化对N80钢腐蚀行为的影响规律及机理。方法 利用自制高温高压多相流冲刷腐蚀环路装置模拟不同流速(0、0.5、1.0、2.0 m/s)的注多元热流体环境,采用失重法计算不同流速下N80钢的平均腐蚀速率,并同时进行原位电化学测试。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对不同流速条件下N80钢腐蚀后的腐蚀产物物相组成和表面微观形貌进行分析。结果 N80钢在注多元热流体环境中的平均腐蚀速率随着流速增加而增大。流速增加影响O2的扩散传质过程、近表面离子分布和壁面剪切力的大小,使腐蚀产物膜特征发生变化。0 m/s时,腐蚀产物主要由FeCO3和少量Fe2O3组成,为单层膜结构,腐蚀形态为均匀腐蚀。0.5~2.0 m/s范围内,腐蚀产物种类增加,主要由FeCO3、Fe2O3和少量FeO(OH)组成,呈双层膜结构,同时N80钢表面腐蚀产物膜出现鼓泡,且随流速增加鼓泡数量增加,去除腐蚀产物膜后发现鼓泡下方存在局部腐蚀。原位电化学测试结果表明:随着流速增加,塔菲尔极化曲线的阳极斜率增大,阴极斜率减小。电化学阻抗谱测试结果表明,N80钢表面外层腐蚀产物膜电阻Rf1、电荷转移电阻Rct和扩散电阻W随流速增加而减小。结论 流速增大加快了O2的扩散传质过程,使得腐蚀电化学控制步骤由阴极氧扩散过程转变为阳极溶解过程,且试样表面保护性FeCO3膜厚度减小,导致产物膜保护性降低。另外,Fe²⁺更容易被氧化形成Fe³⁺,局部FeCO3被氧化成为Fe2O3,破坏了内层膜的完整性,导致局部腐蚀发生。     

Corrosion resistance of the anti‐sulfide steel in the CO2/H2S containing solutions

The present work primarily investigates the corrosion characterization of the common P110 steel and the anti‐sulfide P110SS steel in CO₂‐containing solution with or without hydrosulfuric acid (H₂S) at 70 °C. The electrochemical techniques such as potentiodynamic polarization sweep and electrochemical impedance spectroscopy (EIS) were used to disclose the differences of the corrosion mechanisms between both P110 and P110SS steels in CO₂‐containing solution with various additions of H₂S. The EIS data fitted by ZsimpWin software were analyzed and discussed. The experimental results indicated that H₂S could accelerate and also inhibit the corrosion attack according to the changes of corrosive environments.     

Inhibition of CO2 Corrosion of X52 Steel by Imidazoline-Based Inhibitor in High Pressure CO2-Water Environment

The influence of imidazoline-based inhibitor on the formation, microstructure, and thickness of the corrosion product film that formed on X52 steel after exposure in an environment of high pressure CO₂ containing formation water at high temperature was studied by using weight loss measurement, linear polarization resistance, scanning electron microscopy, energy dispersive x-ray, x-ray diffraction, and x-ray photoelectron spectroscopy. The results showed that the inhibitor significantly influenced the surface morphology and thickness of the corrosion product film. The severity of localized corrosion (pitting) increased with decreased inhibitor concentration. Inhibitor efficiency was observed to be strongly affected by the concentration of inhibitor and CO₂ pressure. The corrosion product film was mainly composed of FeCO₃.     

铝合金浮动式双轴肩FSW接头组织性能分析

对12 mm厚6082-T6铝合金浮动式双轴肩搅拌摩擦焊接头微观组织及力学性能进行了分析研究.结果表明,焊核区发生了动态再结晶和沉淀相溶解,热影响区晶粒和沉淀相粗化;沿焊缝横截面硬度的分布呈高-低-高-低-高的W形分布趋势,且接头沿厚度方向上、中、下层硬度分布趋势较为一致,硬度最低值出现在热影响区;断口形貌分析表明,接头断裂模式为韧-脆混合型断裂;主轴旋转频率600 r/min,焊接速度为300 mm/min,搅拌头倾角为0°时,接头抗拉强度达到了231 MPa,可达母材的79%.     

Inhibition mechanism of sodium laurate to underdeposit corrosion of carbon steels in NaCl solutions

Abstract

In a self-designed occluded corrosion cavity (OCC) simulated cell, the inhibition mechanism of sodium laurate (C₁₂H₂₃O₂Na) to the underdeposit corrosion of the N80 steel in a neutral 0·2 mol L^–1 NaCl solution was studied by electrochemical methods, including measurements of polarisation curves, coupling currents, polarisation resistances, electrochemical impedance spectra (EIS) and ion selectivity of the scale film. The results show that C₁₂H₂₃O₂^– could form a monomolecular adsorption film on the N80 steel surface in the studied solution, whose adsorption behaviour would follow Flory–Huggins isotherm model, and inhibit both anodic and cathodic processes. C₁₂H₂₃O₂^– displays good inhibition performance to the underdeposit corrosion of the N80 steel in the studied system, which could be mainly attributed to the inhibition to the electrode processes of the bulk cathode and occluded anode, the increase in the resistance of the corrosion deposit layer and the prevention to the autocatalysing acidification effect in OCC. The last two factors might be related to the conversion of the deposit layer from anion selectivity to cation selectivity and the formation of a hydrophobic layer on the wall of the micropores in the deposit layer by adsorption of C₁₂H₂₃O₂^–.     

Q125级套管钢高频电阻焊接头耐CO2/H2S腐蚀行为

采用SEM,EBSD和电化学等手段研究了Q125级石油套管钢高频电阻焊接头的耐CO₂/H2S腐蚀行为.结果表明,Q125级套管钢高频电阻焊接头处母材的耐腐蚀性能最好,热影响区次之,而焊缝的耐腐蚀性能最差,导致高频电阻焊接头在CO₂/H₂S腐蚀环境中产生了沟槽腐蚀.试验钢焊缝处的大角晶界比例高于母材和热影响区,从而使焊缝区反应速度常数高于母材和热影响区,这是焊缝区腐蚀速率最高的一个重要原因.通过电化学分析表明,焊缝处的电极反应的极化阻力最小,腐蚀反应易于发生;而母材的电极反应的极化电阻最大,腐蚀反应不易进行,这与腐蚀试验所得结果及极化曲线分析结果一致.     

Fatigue crack growth behaviour of 4130X steel in H2S environment

Abstract

Fatigue crack growth rates of 4130X steel used for compressed natural gas vessels were investigated in this paper. Considering the operating conditions, corrosion fatigue tests at a low frequency of 0·0067 Hz, in H₂S saturated, H₂S unsaturated and air environments were conducted on modified wedge opening load specimens by using a home made low cycle fatigue test system. Curve fitting was applied to the fatigue test data of da/dN–ΔK according to Paris formula. A correlation study between fracture surface and stress intensity factor range was conducted and K values for three stages in different environments were characterised quantitatively. The results show that da/dN in H₂S environment is more than 20 times faster than in an air environment. When the H₂S concentration reaches a certain range, the increase of da/dN becomes slower than that of the H₂S concentration. da/dN differs by 2·4 times while the concentration differs by 11 times. The corrosive environment accelerates the fatigue failure.     

Stainless Steel Bipolar Plates Deposited with Multilayer Films for PEMFC Applications

A chromium nitride (CrN, Cr₂N)/chromium (Cr)/indium-tin-oxide (ITO) system and a gold (Au)/titanium (Ti) system were separately deposited using a sputtering method and an E-beam method, respectively, onto stainless steel 316 and 304 plates. The XRD patterns of the deposited stainless steel plates showed the crystalline phase of typical indium-tin oxide and of metallic phases, such as chromium, gold, and the metal substrate, as well as those of external chromium nitride films. The nitride films were composed of two metal nitride phases that consisted of CrN and Cr₂N compounds. The surface morphologies of the modified stainless steel bipolar plates were observed using atomic force microscopy and FE-SEM. The chromium nitride (CrN, Cr₂N)/chromium (Cr)/indium-tin-oxide (ITO) multilayer that was formed on the stainless steel plates had a surface microstructural morphology that consisted of fine columnar grains 10 nm in diameter and 60 nm in length. The external gold films that were formed on the stainless steel plates had a grain microstructure approximately 100 nm in diameter. The grain size of the external surface of the stainless steel plates with the gold (Au)/titanium (Ti) system increased with increasing gold film thickness. The electrical resistances and water contact angles of the stainless steel bipolar plates that were covered with the multilayer films were examined as a function of the thickness of the ITO film or of the external gold film. In the corrosion test, ICP-MS results indicated that the gold (Au)/titanium (Ti) films showed relatively excellent chemical stability after exposure to H₂SO₄ solution with pH 3 at 80 °C.     

On the protection of carbon steels from hydrogen-sulfide corrosion with mixtures of volatile and contact inhibitors

The effects of volatile (IFKhAN-118) and contact inhibitors (aliphatic primary amine, diphenylguanidine (DPG), and a quaternary ammonium salt (QAS)) and their 1:1 and 2:1 mixtures on the corrosion and electrochemical behavior of carbon steels in an aqueous electrolyte (0.5% NaCl + CH₃COOH (0.25 g/l) + H₂S (2 g/l); pH 3.6) were studied. It was found that QAS is most effective among the individual inhibitors. As regards mixed inhibitors, steels were best protected by IFKhAN-118 + QAS (2:1) and slightly worse by IFKhAN-118 + Amine (2:1). The mixture DPG + VCI was less effective. The protective films of IFKhAN-118 + Amine (2:1) exhibited the aftereffect on steel in an atmosphere of moist H₂S for 10 days (Z = 97 to 98%); however, a relatively long period of time (about 5 days) was required for the formation of stable adsorbed films in the vapor phase of the inhibitor. Original Russian Text ? Yu.I. Kuznetsov, L.V. Frolova, E.V. Tomina, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 2, pp. 160–166.     

Inhibition of hydrogen sulfide corrosion of steel by catamin AB

The protective properties of a quaternary ammonium salt (dimethyl alkyl benzyl ammonium chloride, or catamin AB) have been studied in wide intervals of concentrations of H₂S (from 10 to 2000 mg/l) and of the inhibitor (from 25 to 500 mg/l). It is shown that catamin AB, which effectively slows down the corrosion of steels and preserves their plastic properties in aqueous solutions saturated by hydrogen sulfide to approximately = 2000 mg/l, does not possess high protective properties in the same solutions at = 0.0−50.0 mg/l. According to the results of XPS studies, this fact is connected to the weak adsorption of this inhibitor on the surface of steel in the absence of a film of iron sulfides on it. Based on the XPS data, it has been shown that, in media containing high concentrations of H₂S, a thin (a few nanometers thick) film of iron sulfides is formed on steel. This film is covered with a monomolecular layer of catamin AB, impeding the dissolution of the steel and further growth of the sulfide film. Original Russian Text ? L.V. Frolova, E.V. Tomina, L.P. Kazanskii, Yu.I. Kuznetsov, 2008, published in Korroziya: Materialy, Zashchita, 2007, No. 7, pp. 22–27.     

Nitrogen-based corrosion inhibitor film study using weight loss and electrochemical methods in static and turbulent conditions

There is an increasing demand from oil and gas industry to ensure the integrity of assets and the enviroment in the critical conditions found in presalt wells. This study evaluates new formulations of corrosion inhibitors with different types and alkoxylation degrees of nitrogen-based inhibitors to assess corrosion behavior of carbon steel (API X65). For these studies, corrosion rates were determined through measurements of weight loss and linear polarization resistance (LPR). In the case of electrochemical measurements, experiments were carried out in a laminar flow and in a turbulent flow regime. All data were collected in the presence of CO₂ and CO₂/H₂S mixtures. The results revealed that corrosion protection of carbon steel critically depends on the nitrogen-based inhibitor's alkoxylation type and degree as well as the condition to which they are exposed. It was possible to notice that an ethoxylated amine whose inhibition efficiency in the presence of CO₂ was about 10%, when exposed to H₂S environment at the same temperature showed an efficiency of 86%. It was also observed that the inhibitor with a higher ethoxylation degree presented better efficiencies than the one with a lower degree.