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Commodity Chemicals
INTRODUCTION ABSTRACT A new approach was developed for achieving a low electrochemical corrosion potential (ECP) on structural materials exposed to high-temperature water, even without the addition of pure hydrogen. This approach uses metal hydride or alcohol acting as an alternate hydrogen source as well as providing an insulating oxide surface. Preliminary experimental data on various materials showed that the addition of these alternate reductants lowers ECP and enhances the catalytic bene?t of noble metal-treated surfaces. During the operation of boiling water reactors (BWR) under normal water chemistry (NWC) conditions containing high oxygen concentrations, stress corrosion cracking (SCC) of structural materials, such as sensitized Type 304 (UNS S30400)(1) stainless steel (SS), is known to be a major materials performance problem. It has been reported that SCC susceptibility in BWR is in?uenced by the corrosion potential, which is controlled by the concentrations of oxidizing and reducing species. The electrochemical corrosion potential (ECP) is also affected by the electronic conductivity of oxide ? lms formed on metals in high-temperature water, since electron insulating ? lms on metal surfaces cause a low corrosion potential to be formed. By lowering the corrosion potential of SS to below a critical potential (230 mV vs. standard hydrogen electrode [SHE]) the susceptibility to SCC is markedly reduced (Figure 1).1 The ECP is the mixed potential associated with the equilibrium of redox reactions occurring on a metal surface and the metal oxidation. In BWR water, cathodic currents associated with the reduction of oxygen (O2) and hydrogen peroxide (H2O2) are balanced by anodic currents involving hydrogen oxidation and corrosion of the metal. The corrosion current for Type 304 SS slowly decreases over months of exposure in a reactor water as the oxide thickness on the surface increases with time.
- Energy > Power Industry > Utilities > Nuclear (0.83)
- Materials > Metals & Mining (0.71)
- Energy > Oil & Gas (0.67)
- Materials > Chemicals > Commodity Chemicals (0.53)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.67)
ABSTRACT Antimony is finding use in semiconductor technology for making infrared detectors, thin film capacitors,1 and photoanodes.2 It greatly increases the hardness and mechanical strength of lead and so it is used as an alloying additive in lead alloys for grids in lead-acid batteries.3 The corrosion processes at open-circuit conditions were investigated in acid solutions by Laitinen, et al.4 The authors found that Sb dissolution at opencircuit conditions is coupled to oxygen reduction via the hydrogen peroxide (H2O2) route. At open-circuit conditions, Sb is covered with an oxide film formed by a field-controlled process.5 Anodic polarization increases the electric field across the film and leads to film growth by ionic conductivity.5 The potential of an Sb electrode is a corrosion potential and it is therefore of primary interest to know the nature of the different reactions that might occur at its surface. Studies of the chemistry of Sb emphasize mainly the formation of barrier-insulating oxide films in a range of electrolytes.5-9 Many investigators have focused their attention on the stability and the dissolution reactions of these oxide films. There is agreement that the anodic oxide films electroformed on the Sb electrode under potentiodynamic or galvanostatic conditions consist of an inner porous antimony oxide (Sb2O3) layer and an outer antimony pentoxide (Sb2O5) layer. The experimental findings showed that the nature and stability of the antimony oxide film are functions of different parameters like formation medium, dissolution medium, formation voltage, formation current density, and temperature.8-9 In a recent work, Pavlov, et al., used an ellipsometric technique to investigate the nature and stability of oxide films formed on Sb electrodes.10 The authors found that potentiodynamic oxidation of Sb takes place within two potential regions. They also observed a break in the chronopotentiometric (E-t) curves in the 3-to-4-voltage range during galvanostatic anodic oxide growth. The authors attributed these findings to anodic growth of
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ABSTRACT The susceptibility to stress corrosion cracking (SCC) of Type 321 (UNS S32100) stainless steel (SS) under simulated petrochemical conditions containing thiosulfate and chloride (20 wt% sodium chloride [NaCl] + 0.01 M sodium thiosulfate [Na2S2O3], pH = 2) was assessed using the slow strain rate tensile (SSRT) test and static load (U-bend) tests at the free corrosion potentials. In the SSRT, effects of environmental 2 factors, such as chloride (Cl) plus thiosulfate (S2O3 ), Cl concentration, solution pH, and temperature, on the susceptibility to SCC of Type 321 SS were critically examined. In addition, factorial design experiments using Yates's algorithm quantitatively estimated the individual and interactive effects of temperature, Cl concentration, and solution pH on the SCC susceptibility of Type 321 SS. In the U-bend tests, specimens were immersed in an autoclave containing deaerated 20 wt% NaCl + 0.01 M Na2S2O3 aqueous solution (pH = 2) for 1,400 h at either 80°C or 300°C. Results of the SSRT tests indicated that the effects of environmental factors on the SCC susceptibility of Type 321 SS decreased in the following order: temperature effect >> solution pH effect > Cl concentration effect. The mechanism of SCC induced by corrosion pits or titanium carbide (TiC) particles (5 µm to 10 µm) is discussed. In addi Corrosion has always been a problem in the petroleum refining and the petrochemical operations. The petrochemical process elements, such as furnace tubes, valves, and pipelines, frequently perform at high temperatures and in severely corrosive environments; therefore, heat- and corrosion-resistant alloys, e.g., austenitic stainless steels, have been used widely in the petrochemical industries because of their excellent mechanical strength and toughness. However, in chloride-containing, high-temperature environments, pitting, crevice corrosion, and stress corrosion cracking (SCC) are often associated with the operation.1-5 In addition, it was found that the factors most affecting corrosion of structural materials in the petrochemical industry are chloride (Cl) and hydrogen sulfide (H2S).6-10 H2S is an important constituent of refinery sour waters and is formed by the decomposition of organic sulfur compounds that are present at elevated temperatures.10-13 The Type 321 (UNS S32100)(1) stainless steel (SS) used in this study was a titaniumstabilized austenitic SS. Sensitization (the precipita-
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- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Oil & Gas > Downstream (1.00)
ABSTRACT One of the most difficult areas in which to replace chromate conversion coatings is in the aerospace industry. The difficulties relate primarily to the corrosion performance requirements (which are the strictest of any industry) combined with the widespread use of some of the most corrosion-prone of the aluminum alloys. This has slowed progress toward finding a single-step "drop-in" replacement for chromate.1 In the pursuit of less hazardous alternatives to chromate conversion coating processes, a number of transition metal oxyanions have been investigated,2 including permanganate. Bibber has published a range of studies related to the protection of Al using permanganate, including the incorporation of permanganate into boehmite (AlOOH) coatings,3 sealing of anodized coatings,4 and the generation of true conversion coatings.5-7 Although boehmite-type coatings have shown some promise in trials for aerospace applications,3 their high operating temperatures and relatively long processing times make them less attractive as chromate replacements.1,8 Permanganatebased conversion coatings require lower operating temperatures and shorter processing times,5-7 and despite the necessity to use a barrier seal to pass unpainted neutral salt spray (NSS) performance testing, these coatings show promise as potential replacements for chromate in the aerospace industry.1 The permanganate conversion coating is generated in a seven-step process, involving a solvent clean, alkaline clean, rinse, deoxidation, rinse, treatment in
- Aerospace & Defense (1.00)
- Materials > Metals & Mining > Aluminum (0.61)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.34)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (0.71)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (0.71)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.70)
ABSTRACT Ethanol (C2H5OH) is used as a gasoline additive, serving both as an octane enhancer and an oxygenate to promote complete combustion and reduce harmful emissions. The specifications and procedures for handling fuel ethanol have been described in a document published by the Renewable Fuels Association (RFA).1 The RFA-recommended standard for fuel ethanol is governed by ASTM D 4806.2 The ethanol quality specification under ASTM D 4806 is given in Table 1. ASTM D 4806 also restricts the type of denaturant to be natural gasoline, gasoline components, or unleaded gasoline. The purpose of the denaturant is to render the ethanol undrinkable. For this study, unleaded gasoline was used as the denaturant. Furthermore, ASTM D 4806 cites California and Federal ethanol requirements that limit the ethanol sulfur content to 10 ppm, benzene (C6H6) to 10 vol%, olefins (CnH2n) to 0.5 vol%, and aromatics to 1.7 vol%. Somewhat similar fuel ethanol standards exist in other countries with either more or less restricted water contents.3 It must be noted that the pHe is a measured value using the specific procedure described in ASTM D 6423.2 The value measured using this procedure is time-dependent and does not correspond to equilibrium or even a steady-state hydrogen activity. The RFA fuel ethanol guidelines1 further recommend the addition of one of a number of corrosion inhibitors. Among the nonaqueous environments, the stress corrosion cracking (SCC) of steel in anhydrous ammonia (NH3) and methanol (CH3OH) are well known. The
ABSTRACT Corrosion is one of the most serious problems in the oil and gas production and transportation industry. The environmental conditions in oilfield systems can be very different, but they can be generally summarized as follows: --anaerobic conditions, --a high concentration of carbon dioxide (CO2), --high salinity, and --a variable concentration of sulfides.1-2 Depending on environmental composition, different forms of corrosion can take place in oil and gas wells and flow lines.3 Among them, CO2 corrosion, usually called sweet corrosion, is one of the most severe because the effect of CO2 and/or carbonic acid (H2CO3) can enhance the electrochemical cathodic reaction.4-6 The use of corrosion inhibitors is currently used to protect against corrosion in all petrochemical facilities in the world, because it is cost-effective and flexible.7-8 The total consumption of corrosion inhibitors in the United States has doubled from approximately $600 million in 1982 to nearly $1.1 billion in 1998.9 It also has been reported that the U.S. market for corrosion inhibitors is estimated to be up to $1.6 billion per year by the year 2006.10 Some of the most effective corrosion inhibitors for oil and gas pipeline application are the fatty acid imidazolines. The general chemical structure of imidazoline inhibitors is shown in Figure 1. It consists of three parts: a five-atom ring with two nitrogen elements (part A), a pendant side chain with a functional group (part B), and a long hydrocarbon chain (part C). The inhibition mechanism of imidazoline inhibitors is poorly understood and some discrepancies can be observed in the main literature.11-17 It can be depicted as follows:
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
ABSTRACT Polymer/nano-particle composites are attracting considerable attention because of their unique properties resulting from the nano-scaled microstructures.1-2 The large fraction of atoms that reside at the surface of the nano-scale particles leads to strong interfacial interactions with the polymer matrix, which can improve the protective characteristics of organic coatings.3 Hegedus and Kamel4 also considered that the pigments, which induced a very strong polymer-filler interaction, resulted in coatings with a better dispersion of pigments and stability, resistance to salt spray, and barrier properties. They believed that the extensive interactions between the filler and polymer could decrease the permeability and increase the rigidity of the polymer matrix. Modification of the particle is a useful method to improve the interface efficiency of the particles.5-6 The amine functional group or carboxylic functional group can react with epoxy resin to form the crosslinked polymer network. Therefore, it might be reasonable that interfacial interactions between the epoxy resin and nano-particles could be further enhanced by inducing an organic functional group onto the surface of the particles, and the amine functional group or carboxylic functional group, etc. may be proper candidates. In this study, nano-Ti particles were modified using a precipitation process to induce a hydroxyl functional group first on their surface, and then the hydroxyl functional groups were substituted into an amine functional group. Thereafter, the effect of pigments of the surface-modified nano-Ti particles with the amine functional group on the protectiveness of epoxy coatings was evaluated.
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy (1.00)
ABSTRACT Nickel-based alloys are among the most corrosionresistant alloys in a broad range of environments. The amount of chromium and molybdenum present in the alloy has a significant effect on the corrosion properties of the metal. This study examines the influence of chromium and molybdenum on four nickel-based alloys (Table 1), including Alloy 22 (UNS N06022),(1) in various salt brines. UNS N06022 is a highly corrosion-resistant nickel-based alloy, which has a range of uses, including dental implants and in industrial settings where highly corrosive environments are encountered. In general use, Alloy 22 often comes in contact with concentrated brines at elevated temperatures. Alloy 22 was used as a standard alloy, and two ternary alloys were chosen based on the Alloy 22 composition, but with varying amounts of the primary passivating components (chromium and molybdenum). The ternary compositions were Ni-11Cr-7Mo and Ni-11Cr-13Mo. A binary alloy with 20 wt% Cr was also examined. The corrosion resistance of several Ni-Cr-Mo alloys have been discussed in detail.1 In brief summary, Alloys C (UNS N06003), C-276 (UNS N10276), C-4 (UNS N06455), and Inconel Alloy 625 (UNS N06625) have been tested for corrosion resistance in acidic solutions, including hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), hydrofluoric acid (HF), and phosphoric acid (H3PO4). The alloys with higher molybdenum content usually show the best resistance to reducing environments such as H2SO4 and HCl and pitting attacks from chloride-containing solutions, while the alloys with higher chromium content usually have the best resistance to strongly oxidizing solutions such as HNO3.
- Materials > Metals & Mining > Nickel (1.00)
- Materials > Chemicals > Commodity Chemicals (0.88)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
ABSTRACT Nowadays, natural compounds such as herb plants are used as inhibitors to develop new cleaning chemicals for a green environment. Herb plants, which usually are used as an herbal medicine, have been selected because they are environmentally acceptable, readily available, and a renewable source for a wide range of needed inhibitors. Plant extracts are viewed as an incredibly rich source of naturally synthesized chemical compounds that can be extracted by simple extract procedures with low cost. Several investigations have been reported using such economic plant extracts. El Hosary, et al.,1 studied the corrosion inhibition of aluminum and zinc in 2 N hydrochloric acid (HCl) using naturally occurring Hibiscus subdariffa (Karkode) extract. The inhibition of the corrosion of steel, aluminum, and copper in HCl, sulfuric acid (H2SO4), and citric acid (C6H8O7) by molasses was also studied,2 and the values of 83% and 13% inhibition efficiencies were obtained for HCl and H2SO4 solutions, respectively, containing 0.75% molasses. Loto3 reported the inhibitive action of Vernonia amygdalina (bitter leaf) on the corrosion of mild steel in 0.5 M HCl at 28°C. Avwiri and Igho studied the inhibitive action of V. amygdalina on the corrosion of aluminum alloys in HCl and nitric acid (HNO3) at concentrations of 0.2 g/L and 0.4 g/L at 29°C.4 They showed that the solution extract of the leaves serves as an excellent inhibitor. The inhibition effect of Zenthoxylum alatum plant extract on the corrosion of mild steel in 20, 50, and 88% aqueous orthophosphoric acid (H3PO4) has been investigated by weight-loss and electrochemi-
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- Health & Medicine (1.00)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (0.97)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (0.97)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (0.67)
ABSTRACT The effects of surface pretreatment on the rate of scribe-creep caused by underpaint corrosion on coated AA2024-T3 (UNS A92024) were investigated. Scribe-creep experiments were conducted on epoxy polyamide-coated (average coating thickness: ~10 µm) AA2024-T3 in 80% relative humidity at 25°C, 40°C, and 50°C. Scribe-creep was observed to be enhanced by exposure test temperature regardless of surface pretreatment with an activation energy of 30 kJ/mol to 40 kJ/mol. The scribe-creep rate was accelerated at all temperatures especially by pretreatments that increased the concentration of surface Cu or left a high capacity for Cu-replating. Sodium hydroxide (NaOH) etching particularly increased the amount of replated Cu at the coated metal interface compared with an as-received condition and a NaOH etch followed by a nitric acid (HNO3) deoxidation. The effect of each surface pretreatment to enhance or retard scribe-creep is traced either to the initial level of Cu replating prior to coating or to its ability to supply Cu for replating in the scribe-creep filament wake. This Cu replating enhances the rate of cathodic electron transfer reactions, which supports the galvanic corrosion process between scribe-creep head and tail. When Cu was eliminated as an alloying element, or when surface Cu was minimized at the coating-metal interface by HNO3 deoxidation pretreatment, scribe-creep corrosion rates were lowered. This was rationalized to occur as a result of a decrease in the cathodic oxygen reduction reaction rate, which supports anodic undercutting at the head of the corrosion front. Al-based precipitation age-hardened alloys containing Cu and Fe are prone to localized corrosion such as pitting induced by galvanic interactions between Curich intermetallic compounds (IMC) and the Al alloy matrix. These local galvanic cells, which induce acid pitting and alkaline attack, are often formed by Cuand Fe-containing intermetallics or replated Cu.1-12 In AA2024-T3 (UNS A92024),(1) pit initiation sites include Al-Cu-Mg particles,2-3,7,11-13 the periphery of Cu-enriched Al-Cu-Mg particles that have been dealloyed of Al and Mg,2 and the matrix adjacent to Al-Cu and Al-Cu-Fe-Mn constituent particles.3,5,10,13 The Al-CuMg type is the most active constituent particle and as much as 60% of the intermetallics on the surface of an AA2024-T3 sample are of the Al-Cu-Mg type,2,14-15 with 2.7% of the total surface covered by these particles.2 The Al-Cu-Mg type IMC is anodic to the Al alloy matrix and is present as 1-µm to 10-µm-diameter particles.16 The smaller particles will dissolve completely, while the larger particles generally undergo selective dissolution of the Al and Mg from the particle, leaving only a fine Cu sponge.2-3,12,15,17-18 The particle becomes cathodic to the matrix with time.2-3,11-12,19-20 Under certain conditions, some authors have observed rings of deposited Cu around these Al-Cu-Mg precipitates, suggesting that they are a major source of Cu for replating.18 The Al-Cu and Al-Cu-Mn-Fe types of IMC also serve as preferred cathodic sites relative to the Al matrix.21 Cu2+ ions dissolved into solution can be reduced readily on these particles and elsewhere.3 The
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
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