Sulfide Corrosion Research Articles

Spontaneous Combustion Tendency of Iron Sulfide Corrosion: Oxidation Characterization and Thermostability

The oxidation characterization and thermostability was studied using X-ray diffraction, Raman analysis and thermo gravimetric–differential scanning calorimetric analysis(TG-DSC). Controlled oxidation experiments were conducted for 30mins, 1hour and 4hours. S-species were characterized and qualified on surface of corrosion particle combine XRD with Raman analysis. Mackinawite FeS transforms into greigite Fe3S4 readily with additional S8 under air atmosphere. Amorphous mackinawite is the initial phase during crystallization and its stability is poor. The thermal behavior of the corrosion is studied in heat rating 10°C/min between ambient and 1000°C using TG-DSC. The mass loss is mainly caused by the release of SO2 between 23 and 397°C. The maximum exothermic intensity occur between 200 and 400°C. Oxidation of mackiwite /greigite releases abundance of heat, which served as a trigger for spontaneously self-ignited.

Inhibition of corrosion and hydrogen permeation into carbon steel in solutions containing hydrogen sulphide and carbon dioxide

The efficiency of ethoxy higher aliphatic amines (EOAs) against carbon dioxide and hydrogen sulphide corrosion and hydrogen permeation into carbon steel in acid solutions has been studied. The influence of the number of ethoxy groups (2, 5 and 14), the length of the hydrocarbon radical (R = C10 – C13 and R = C17 – C20), medium acidity (0.005–0.05 M HCl), and electrode potential was investigated. Concurrently, the influence of higher aliphatic amine bottoms (emulgin) that are a mixture of primary and secondary aliphatic amines was studied. The protective efficiency of EOAs reaches 95–99.9%, hydrogen permeation decreases both at the corrosion potential and under conditions of anodic and cathodic polarization of the steel electrode. The inhibiting effect of emulgin is 96–97%.

SiO2-based nanocontainers of a novel type: If the template micelles are functional, why remove them

A new method is proposed for creating containers based on mesoporous silica nanoparticles for diverse amphiphilic compounds. The method is based on the use of the micelles of required functional compound (i.e., the compound that is subsequently loaded into the containers) as a template when synthesizing nanoparticles. The prospects and advantages of this approach are exemplified by the synthesis of SiO2 particles using the micelles of cetyltrimethylammonium bromide (which can be used as an inhibitor of hydrogen sulfide corrosion) as a template.

Synthesis of hydrogen sulfide corrosion inhibitors for oil production

Pyridinium salts have been synthesized by reacting 2-allyl- and 4-propenylphenoxy(C2–C4)bromoalkanes with pyridine and further examined as inhibitors of hydrogen sulfide corrosion of St3 steel in water-salt systems containing H2S. The dependence of the protective properties of the test compounds on their structure has been revealed. It has been found that N-(2-propenylphenoxytetamethylene)pyridinium bromide exhibits the best inhibitory properties (degree of corrosion protection at a concentration of 100 mg L−1 is 96.0%).

Hydrogen sulfide gas emission under turbulent conditions – an experimental approach for free-fall drops

Odor nuisance and sulfide corrosion in sewers carrying septic wastewater are accelerated at points of turbulence such as drops in manholes, but accurate methods or empirical expressions to evaluate the gas stripping rate at those particular sites are still missing. With the aim of improving the current knowledge on the influence of free-fall drops on the release of hydrogen sulfide gas, an experimental set-up was built allowing different free-fall drops heights and flows. Three types of experiments were carried out: reaeration tests without sulfide; sulfide oxidation tests; and hydrogen sulfide release tests. With the increase of the free-fall drop height or of the flow, a higher rate of air-to-water mass oxygen transfer was observed. Results regarding sulfide oxidation tests with reaeration through the free-fall have shown that the oxidation rate was correlated with flow. In the hydrogen sulfide release tests, the maximum concentration in the atmosphere reached 500 ppm. Results also showed that increasing the flow rate decreased the time at which the maximum concentrations in the atmosphere were observed.

In Situ Synthesis of 2-Phenylbenzimidazole as an Hydrogen Sulfide Corrosion Inhibitor of Carbon Steel

Hydrogen sulfide corrosion inhibition of carbon steel has been evaluated using the combination of benzene-1,2-diamine, benzaldehyde, and FeCl3 to in situ inhibitor synthesis at 25°C using electrochemical and weight-loss studies. The results showed that the corrosion rate of steel decreased significantly by increasing the inhibitor concentration. The concentration of in situ synthesized inhibitor was measured by ultraviolet and visible spectrophotometer (UV-vis). The morphology and composition of the corrosion products were analyzed using scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS). Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of 2-phenylbenzimidazole on the surface by an in situ manner. Quantum chemical studies were applied to investigate the correlation between the molecular structure and inhibition effect of this compound.

High-temperature corrosive damage to superalloys during operation of blades of gas-turbine engines and power plants

The role of liquid nickel-sulfide eutectic in the mechanism of corrosive damage is determined by investigations of products of high-temperature oxidation and corrosion of superalloys with the use of scanning-electron microscopy and X-ray spectroscopic and X-ray structural analyses. It is found that the sulfide corrosion rate is controlled by the process of the dilution of the high-temperature nickel alloy within the liquid nickel-sulfide eutectic, diffusion of alloying constituents of the alloy in the liquid phase, and their subsequent oxidation.

해저 철제유물의 황화물에 의한 부식특성 연구

This study is on the corrosion of iron objects caused by sulfides in undersea environment. The corrosion state of objects in seawater and their damage state after underwater and left in highly humid air were studied. The samples of this study were four iron objects which had been taken out from undersea mud layer located in Taean Mado, Chungcheongnamdo. SEM-EDS and XRD analyse on the objects to check whether they have sulfides or not. The result of analysis suggested that the major component of corrosion product generated in undersea deposit soil is sulfur(S) and iron sulfide(FeS) is formed as sulfide. However, there was no clear corrosion on the surface of objects which was exposed to sea water because of the impact of concretion which covered the surface. In order to check the damage status of iron objects after they had been taken out of sea water, exposure tests in high humidity environment and dehumidified environment were done on the corrosion products. The result of the test suggested that the oxidization of iron sulfide corrosion product makes iron sulfate () and sulfuric acid () and they can cause secondary corrosion of iron objects. Therefore, it is believed that the iron sulfide corrosion product of iron objects taken out from underwater environment should be removed by all means and the keeping environment of the iron objects should also maintain dehumidified state.

Monitoring of anaerobic microbially influenced corrosion via electrochemical frequency modulation

Electrochemical frequency modulation (EFM) is a rather novel technique to monitor corrosion rates in situ, providing direct access to Tafel slopes with only minor polarization. So far EFM has been applied mainly for electrochemical corrosion monitoring in purely chemical corrosion systems with predominant uniform corrosion, but it has also great potential for monitoring microbially influenced corrosion (MIC). Thus, in this study MIC induced by different cultures of sulfate-reducing bacteria (SRB) was monitored with EFM, and compared to results from linear polarization resistance (LPR) and measurements of the free corrosion potential Ecorr. The electrochemical results obtained in small scale bioreactors with a three electrode setup were complemented by chemical analysis and SEM observations. SRB featuring high corrosion rates were compared to non-corrosive but still H2-consuming control SRB, sterile controls and abiotic sulfide corrosion controls. Corrosion rates determined with EFM and LPR were accurate and precise in all cases as long as the system was based on uniform corrosion. However with the onset of localized corrosion both methods fail to predict accurate rates. Unlike other electrochemical corrosion rate measurements, EFM has the advantage to provide indicating ratios in the current response at different frequencies, so-called causality factors, which allow identifying changes in the corrosion system and therefore assessing the accurateness of the obtained results. As a consequence EFM is a promising electrochemical corrosion monitoring technique for MIC in fundamental and applied studies.

Pyrophoric tendency of hydrogen sulfide corrosion product in oil tanks under aerobic condition

The study simulated the sulfidation reaction of Fe2O3 and H2S in oil tanks containing sulfur under aerobic condition. To evaluate the pyrophoric tendency of H2S corrosion product, the oxidation reaction was taken under different temperatures after the sulfidation reaction and the temperature changes were measured during the oxidation process. The results showed that, with the increase of initial O2 concentration in the mixture of sulfidation gas, the oxidation possibility of the sulfidation product in the sulfidation process increased, then the final amount of sulfidation product in the oxidation process decreased, and the pyrophoric reactivity of H2S corrosion product decreased. The higher the initial temperature at which the oxidation of the sulfidation product took place, the faster the temperature of the oxidation reaction rose, and the greater the pyrophoric reactivity of H2S corrosion product.

New, effective carbon dioxide and hydrogen sulfide corrosion inhibitors based on white phosphorus, sulfur, alcohols, and amines

New ammonium salts of dithiophosphoric O,O′-diesters have been obtained by simple and convenient (one pot) methods of synthesis from white phosphorus (P4), elemental sulfur, alcohols, phenols (including hydroxyethylated nonylphenols), and amines. It has been revealed that the ammonium salts of O,O-dialkyl dithiophosphoric acids obtained are effective inhibitors of carbon dioxide corrosion (protective effect Z = 90–99%) and hydrogen sulfide corrosion (Z = 88–89%) of a mild steel. It has been shown that the inhibitory activity against carbon dioxide corrosion depends on neither theamine nature nor the chain length of the alkyl substituent in the ester group and the protective effect in the case of hydrogen sulfide corrosion depends on the nature of the reactant alcohol or amine and may slightly decrease (by 10–15%). An advantage of these inhibitors is that their protective effect in carbon dioxide corrosion is enhanced with temperature (30–80°C), rather than decreases.

Changes in the structure and properties of low-carbon low-alloy pipe steels upon inoculation with REM

The influence of REM additives on the structure, mechanical properties and corrosion resistance of low-carbon low-alloy steels is studied. The effect of inoculation with rare-earth metals on the content of sulfur and oxygen in the steels and on the degree of their contamination with nonmetallic inclusions are investigated. The resistance of the steels to stress sulfide corrosion cracking, hydrogen cracking and total, local, carbon dioxide and bacterial corrosion is determined.

Ferric iron amendment increases Fe(III)-reducing microbial diversity and carbon oxidation in on-site wastewater systems

Onsite wastewater systems, or septic tanks, serve approximately 25% of the United States population; they are therefore a critical component of the total carbon balance for natural water bodies. Septic tanks operate under strictly anaerobic conditions, and fermentation is the dominant process driving carbon transformation. Nitrate, Fe(III), and sulfate reduction may be operating to a limited extent in any given septic tank. Electron acceptor amendments will increase carbon oxidation, but nitrate is toxic and sulfate generates corrosive sulfides, which may damage septic system infrastructure. Fe(III) reducing microorganisms transform all major classes of organic carbon that are dominant in septic wastewater: low molecular weight organic acids, carbohydrate monomers and polymers, and lipids. Fe(III) is not toxic, and the reduction product Fe(II) is minimally disruptive if the starting Fe(III) is added at 50–150mgL−1. We used 14C radiolabeled acetate, lactate, propionate, butyrate, glucose, starch, and oleic acid to demonstrate that short and long-term carbon oxidation is increased when different forms of Fe(III) are amended to septic wastewater. The rates of carbon mineralization to 14CO2 increased 2–5times (relative to unamended systems) in the presence of Fe(III). The extent of mineralization reached 90% for some carbon compounds when Fe(III) was present, compared to levels of 50–60% in the absence of Fe(III). 14CH4 was not generated when Fe(III) was added, demonstrating that this strategy can limit methane emissions from septic systems. Amplified 16S rDNA restriction analysis indicated that unique Fe(III)-reducing microbial communities increased significantly in Fe(III)-amended incubations, with Fe(III)-reducers becoming the dominant microbial community in several incubations. The form of Fe(III) added had a significant impact on the rate and extent of mineralization; ferrihydrite and lepidocrocite were favored as solid phase Fe(III) and chelated Fe(III) (with nitrilotriacetic acid or EDTA) as soluble Fe(III) forms.

Corrosion inhibitors based on regenerated plant raw material for protection of gas and oil recovery equipment

Technology is developed and introduced for preparing a highly efficient corrosion inhibitor based on regenerated plant raw material for protecting gas and oil industry equipment, and supply lines from internal surface corrosion, hydrogenation, and sulfide corrosion cracking, caused by the action of hydrogen sulfidecontaining mineralized aqueous media. Alongside research into the choice of the most stable and economically justified materials and corrosion-resistant coatings used under specific conditions, a significant place is occupied by creation and use of various corrosion inhibitors. However, universal corrosion inhibitors have not so far been found, although a considerable number of new inhibitors have been created for each specific purpose. In Russia and throughout the world, there is some reduction in the use of inhibitors in connection with the spread of production equipment and pipelines manufactured from corrosion-resistant materials, and also with use of corrosion-resistant coatings. In spite of this, the field of application for inhibitors remains considerable. Analysis of the contemporary state of the problem for creation of corrosion inhibitors indicates that with some certainty it is possible to predict a class of compounds that to some measure will exhibit inhibiting properties in some corrosion situation. Currently, for protecting metals of oil industry equipment from hydrogen sulfide corrosion in strongly mineralized media 2-alkyl imidazolene derivatives, prepared by reaction of polyamines with carbonic acids followed by ring formation in a five-membered imidazolene heterocycle, are often used. Corrosion inhibitors, prepared on the basis of 2-alkylimidazolenes from polyethylene polyamides (PEPA) and 2-methyl2-alkylhexane acids at 240‐280°C [1], and also from a mixture of 1-dimethylaminoethyl- and (aminoethyl)-2-isoalkyl-2-imidazolenes [2], exhibit low colloidal-chemistry properties, often stratified during shipment and storage, and capable of being salted out during use in highly-mineralized hydrogen sulfide-containing media. A specific disadvantage is displayed by a corrosion inhibitor that is a mixture of 2-alkyl imidazolene derivatives and amides of higher isomeric α-branched monocarbonic acids (HIA) with aromatic hydrocarbons, surface-active substances (SAS), and alcohols [3]. Disadvantages of these corrosion inhibitors are an increased capacity for foaming, use of expensive aromatic hydrocarbons, and insufficient efficiency in the later and concluding stages of oil and gas development. Technology for corrosion inhibitor preparation [3] has been developed by us, and inhibitors are produced at the Kaustik company in Sterlitamak under the names Azimut-14, Azimut-14M, and Vikor. Corrosion inhibitor Vikor is classified as a combined action reagent, i.e., an inhibitor and bactericide, and it also protects metal from hydrogenation. Use of this inhibitor provides suppression of dangerous micro-organism corrosion development, and protection of equipment from the corrosive action of oil industry media. We have also developed technology for preparation of a corrosion inhibitor intended for protecting gas- and oilrecovery equipment operating in highly mineralized hydrogen sulfide-containing media, with the attraction of less expensive

Inhibition of hydrogen sulfide corrosion of steel in gas phase by tributylamine

The paper is devoted to studying the possibility of application of tributylamine (TBA) as volatile inhibitor of hydrogen sulfide corrosion (HSC) of steels. The influence of С(H2S), pH and temperatures on TBA protective action is studied as well. Amine adsorption on steel surface modified by sulfide has been investigated and TBA impact on its composition and structure has been reviewed using a number of electrochemical methods, ellipsometry and XPS. The contributions of corrosion products and inhibitor films to the total protective effect have been estimated on the basis of the developed method.

Analysis on Backside Cracks in 316LMod Inner Linings of Urea Reactors

Backside cracks were found universally in the ultra-low carbon austenitic stainless steel (316LMod) inner linings of urea reactors in recent years, and led to urea reactors leakage. Analyses on the sample revealed that, the backside cracks were caused by the interaction of wet hydrogen sulfide (H2S) and chloride ions (Cl-) stress corrosion cracking (SCC), and H2S played a dominant role. The source of H2S and chloride ions was the leak detection steam. Furthermore, measures to avoid backside cracks in 316LMod inner linings of urea reactors were put forward and verified.

Sulphide production and corrosion in seawaters during exposure to FAME diesel

Experiments were designed to evaluate the corrosion-related consequences of storing/transporting fatty acid methyl ester (FAME) alternative diesel fuel in contact with natural seawater. Coastal Key West, FL (KW), and Persian Gulf (PG) seawaters, representing an oligotrophic and a more organic- and inorganic mineral-rich environment, respectively, were used in 60 day incubations with unprotected carbon steel. The original microflora of the two seawaters were similar with respect to major taxonomic groups but with markedly different species. After exposure to FAME diesel, the microflora of the waters changed substantially, with Clostridiales (Firmicutes) becoming dominant in both. Despite low numbers of sulphate-reducing bacteria in the original waters and after FAME diesel exposure, sulphide levels and corrosion increased markedly due to microbial sulphide production. Corrosion morphology was in the form of isolated pits surrounded by an intact, passive surface with the deepest pits associated with the fuel/seawater interface in the KW exposure. In the presence of FAME diesel, the highest corrosion rates measured by linear polarization occurred in the KW exposure correlating with significantly higher concentrations of sulphur and chlorine (presumed sulphide and chloride, respectively) in the corrosion products.

Failure Analysis of the Entrance Elbow for Crude Oil Cracking Furnace

The weld cracking mechanism of the entrance elbow of crude oil cracking furnace served at 490°C was investigated. The performance and microstructure of failed elbow were characterized by hardness testing, optical microscopy, scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The results showed that cracks are caused by the combination of sulfide corrosion, embrittlement of weld metal and thermal stress.

A critical assessment of the efficacy of biocides used during the hydraulic fracturing process in shale natural gas wells

We examined the efficacy of multiple biocides that are commonly used to control sulfate-reducing bacteria in fracturing fluids in shale natural gas formations. Seven biocides (tetrakis [hydroxymethyl] phosphonium sulfate, sodium hypochlorite, didecyldimethylammonium chloride, tri-n-butyl tetradecyl phosphonium chloride, glutaraldehyde, a glutaraldehyde and alkyldimethylbenzylammonium chloride blend, and a glutaraldehyde alkyldimethylethylbenzylammonium chloride blend) were examined. Minimum inhibitory concentrations (MIC) were determined using planktonic cells and biofilms of Desulfovibrio desulfuricans strain G20 and a sulfate-reducing enrichment culture that was obtained from a Barnett Shale frac pond. All biocides had higher MIC values for biofilms compared to planktonic cells from these two cultures. Higher concentrations of all biocides, except didecyldimethylammonium chloride, were required to kill planktonic cells of G20 that were exposed to humic acid. These results clearly indicate that biofilm formation by sulfate-reducing bacteria, as well as organic loading rates, negatively impact the efficacy of biocides. This work provides valuable information concerning the effects of biofilm formation and organic loading on biocide MIC values. These MIC data can be used as a guide for the control of microbial growth in future frac jobs, which should result in fewer incidences of sulfide production and corrosion in shale natural gas wells.

Elevated corrosion rates and hydrogen sulfide in homes with ‘Chinese Drywall’

In December 2008, the U.S. Consumer Product Safety Commission (CPSC) began receiving reports about odors, corrosion, and health concerns related to drywall originating from China. In response, a detailed environmental health and engineering evaluation was conducted of 41 complaint and 10 non-complaint homes in the Southeast U.S. Each home investigation included characterization of: 1) drywall composition; 2) indoor and outdoor air quality; 3) temperature, moisture, and building ventilation; and 4) copper and silver corrosion rates. Complaint homes had significantly higher hydrogen sulfide concentrations (mean 0.82 vs. <LOD μg/m3, p<0.05), and significantly greater rates of copper sulfide and silver sulfide corrosion compared to non-complaint homes (Cu2S: 476 vs. <32Å/30d, p<0.01; Ag2S: 1472 vs. 389Å/30d, p<0.01). The abundance of carbonate and strontium in drywall was also elevated in complaint homes, and appears to be useful objective marker of problematic drywall in homes that meet other screening criteria (e.g., constructed or renovated in 2006–2007, reports of malodor and accelerated corrosion). This research provides empirical evidence of the direct association between homes constructed with ‘Chinese Drywall’ in 2006–2007 and elevated corrosion rates and hydrogen sulfide concentrations in indoor air.