ISSN 2305-6894

2015, Vol. 4, Issue 3 (pp. 197–283)

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New hibernation systems for corrosion protection of internal substrate surfaces of chemical processing plants

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1 Northern Technologies International Corporation, 23205 Mercantile Rd., Beachwood, OH 44122, USA
2 Zerust, 255, São Bernardo Do Campo Avenue, Sorocaba 18085, São Paulo, Brazil
3 Petrobras, República do Chile Av., Nr. 65, Rio de Janeiro – RJ, CEP: 20031-912, Brazil

Abstract: Corrosion protection of large equipment’s internal surfaces (distillation towers, pipelines, tanks, boilers, heat exchangers, etc.) during storage, transportation/shipping and long term mothballing (up to 10 years) is a worldwide problem. In many cases, well-known technology for replacement of the environment with nitrogen gases cannot be applied and are not always efficient enough. In addition to their limited protection ability, these approaches tend to be cumbersome, complicated, labor intensive, very expensive and create safety issues. This paper describes a system that reduces the environment corrosiveness by decreasing the relative humidity (RH) to a level that allows achieving corrosion protection of different metals in any sealed enclosures. In addition this new system delivers the volatile corrosion inhibitors (VCI) into enclosures that increases the corrosion protection efficiency and decreases the corrosion if the enclosures have some leakage. This system creates the required RH and concentration of VCI very fast. It is compact equipment and can be moved for applying corrosion protection in different locations. In the paper, we will present a mobile system that can be periodically used for many kinds of equipment in different facilities. A real system, designed, manufactured and applied for corrosion protection of mothballing equipment in one refinery will be presented and discussed.

Int. J. Corros. Scale Inhib., , 3, 197-209 PDF (2 220 K)
doi: 10.17675/2305-6894-2015-4-3-197-209

Oil-based preservative materials for protection of copper against corrosion in atmospheres containing SO2

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1 Russian Scientific Research Institute of Use of Machinery and Oil Products, Novo-Rubezhnyi per., 28, Tambov, 392022, Russian Federation
2 Tambov State Technical University, Sovetskaya Str., 106, Tambov, 392000, Russian Federation
3 Derzhavin State University, Internatsyonalnaya Str., 33, Tambov, 392000, Russian Federation

Abstract: The protective efficiency of oil coatings modified by a gun lubricant against copper corrosion in an atmosphere containing sulfur dioxide (up to 5 vol.%) has been studied. The influence of the oil nature, additive concentration, relative humidity (70–100%) and equilibrium SO2 concentration in the air was investigated. The protective effect of the formulations is up to 90% under particularly corrosive conditions.

Int. J. Corros. Scale Inhib., , 3, 210-220 PDF (1 047 K)
doi: 10.17675/2305-6894-2015-4-3-210-220

Corrosion behavior of low carbon steel in technological aqueous calcium nitrate solutions

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1 Physical Chemistry Department, Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006, Russian Federation
2 Inorganic Chemistry and Chemical Technologies Department, Voronezh State University of Engineering Technologies, pr. Revolutsii, 19, Voronezh, 394036, Russian Federation

Abstract: The paper demonstrates the inhibitive effect of inorganic and organic additives to calcium nitrate and ammoniated calcium nitrate aqueous solutions on corrosion of low carbon structural steel St3. The steel corrosion behavior was studied by voltammetry. The effect of ammonization as well as of addition of such inhibitors as monoethanolamine and potassium dichromate on the main parameters of the corrosion process was established. The findings will be useful for corrosion control in components made of the steel used in fertilizer industry and also in concrete as reinforcement.

Int. J. Corros. Scale Inhib., , 3, 221-225 PDF (248 K)
doi: 10.17675/2305-6894-2015-4-3-221-225

Modification of bituminous coatings to prevent stress corrosion cracking of carbon steel

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A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation

Abstract: Corrosion-mechanical tests of pipe steel specimens in the presence of organosilanes have been carried out and the effect of the latter on steel cracking resistance under slow strain in NS-4 simulated underfilm electrolyte (рН 6.7), both without and with addition of sulfides, has been determined. It has been shown that organosilanes increase the crack resistance of steel, including that in sulfide-containing media. Comparative laboratory tests have been performed for adhesive strength, water resistance, and resistance to cathodic disbonding of adhesive bonds obtained by the existing technology of pipeline insulation under field conditions and using new methods for pipe surface treatment. It has been found that addition of organosilanes improves the adhesive characteristics of a bitumen-polymeric coating on pipe steel.

Int. J. Corros. Scale Inhib., , 3, 226-234 PDF (855 K)
doi: 10.17675/2305-6894-2015-4-3-226-234

Laboratory assessment of tetrakis(hydroxymethyl)phosphonium sulfate as dissolver for scales formed in sour gas wells

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1 Saudi Aramco, Research and Development Center, Dhahran, Saudi Arabia 31311
2 Saudi Aramco, EXPEC Advanced Research Center, Dhahran, Saudi Arabia 31311

Abstract: Tetrakis(hydroxymethyl)phosphonium sulfate (THPS) is an environmental friendly biocide commonly used in oil fields. It also has been used to control iron sulfide precipitation for water injection and to remove deposits in oil production systems. In this study, THPS was examined as the dissolver for scale deposits formed on downhole tubular of high temperature sour gas wells. These deposits consisted of a wide range of mineral phases and are often dominated with various forms of iron sulfides and iron oxyhydroxides. The THPS based dissolvers were studied at various concentrations, pH values and with different additives. These additives included ammonium chloride, chelating agents and phosphonates. Experimental results indicated that the dissolving power was not proportional to THPS concentration. The maximum dissolution was observed in THPS concentration of 25 to 50%, depending on scale composition. Its dissolving power could be significantly increased with both ammonium chloride and chelating agents. The synergistic effect of ammonium chloride was largely attributed to pH decrease. As a result, the corrosivity of THPS solution to metallurgy was increased with the addition of ammonium chloride. The corrosion rate of mild steel was increased over three times with 4% ammonium chloride added. Contrary to previous reports, phosphonate additives decreased scale dissolution and induced new precipitation. Formation of calcium sulfate precipitates was also observed during dissolution of calcite, which will limit the THPS from scales containing calcium carbonate. This study also revealed the dissolution behavior of different minerals in the THPS solution. Iron oxyhydroxides had the highest dissolution rate, followed by calcite, siderite and pyrrhotite. Pyrite, marcasite and anhydrite were almost insoluble in the tested solutions. Results from this study can be used as guideline for the development and design of THPS based scale dissolvers.

Int. J. Corros. Scale Inhib., , 3, 235-254 PDF (1 222 K)
doi: 10.17675/2305-6894-2015-4-3-235-254

Corrosion inhibition of 1-vinylimidazole-3-phenacyl hexafluoroantimonate salt on mild steel in HCl solution

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Department of Chemistry, College of Sciences, University of Sharjah, Sharjah, P.O. Box: 27272, United Arab Emirates

Abstract: The purpose of this paper is to study by weight loss experiments the effect of 1-vinylimidazole-3-phenacyl hexafluoroantimonate salt (VIPFA) on the corrosion inhibition of mild steel in 1.0 M HCl solution. Weight loss measurements were carried out on mild steel specimens in 1.0 M HCl and in 1.0 M HCl containing various concentrations (5.0·10–4 to 5·10–7 M) of the laboratory synthesized 1-vinylimidazole-3-phenacyl hexafluoroantimonate salt at temperatures ranging from 303 to 343 K. 1-Vinylimidazole-3-phenacyl hexafluoroantimonate salt (VIPFA) was found to be a very efficient inhibitor for carbon steel in 1.0 M HCl solution, reaching about 92 per cent at the concentration of 5.0·10–4 M at 303 K. The percentage of inhibition in the presence of this inhibitor was decreased with temperature which indicates that physical adsorption was the predominant inhibition mechanism because the quantity of adsorbed inhibitor decreases with increasing temperature. From this study, it was concluded that this inhibitor could have application in industries, where hydrochloric acid solutions at elevated temperatures are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary.

Int. J. Corros. Scale Inhib., , 3, 255-268 PDF (1 153 K)
doi: 10.17675/2305-6894-2015-4-3-255-268

Comparative evaluation of biopolymers and synthetic polymers as hydroxyapatite dispersants for industrial water systems

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School of Arts and Sciences, Walsh University, 2020 E. Maple Street, N. Canton, OH 44720, USA

Abstract: The dispersion of hydroxyapatite, Ca5(PO4)3OH, HAP, by a variety of biopolymers and synthetic polymers of different composition and ionic charge has been investigated. The dispersion data show that polymer effectiveness as HAP dispersant strongly depends upon polymer architecture. Results also reveal that synthetic polymers perform better than bio-polymers. It has been found that anionic, non-ionic, amphoteric, and cationic surfactants are ineffective as HAP dispersants. Additionally, it has also been observed that cationic surfactant and cationic polymer exhibit antagonistic effect on the performance of anionic polymeric dispersants.

Int. J. Corros. Scale Inhib., , 3, 269-283 PDF (736 K)
doi: 10.17675/2305-6894-2015-4-3-269-283

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