ISSN 2305-6894

2013, Vol. 2, Issue 2 (pp. 82-161)

Prev. issue<- -> Next issue

Ethoxylated fatty amines as corrosion inhibitors for carbon steel in hydrochloric acid solutions

  • and
1 Chemistry Department, Faculty of Applied Science, Umm Al-Qura University, P.O.Box 118, Makkah Al Mukaramha, Saudi Arabia
2 Mechanical engineering department, College of Engineering, Umm Al-Qura University, P.O.Box 5555, Makkah, 21955 Saudi Arabia

Abstract: The effect of three compounds of non ionic surfactants, namely, ethoxylated fatty amines with different number of ethylene oxide unit on the corrosion of carbon steel (Type L52) in 1 M HCl has been studied using weight loss and galvanostatic polarization measurements. The percentage inhibition efficiency was found to increase with increasing concentration of inhibitor, number of ethylene oxide units and with decreasing temperature. The inhibitive effect of these compounds was interpreted in view of their adsorption on the steel surface, through their ethoxy groups. The adsorption of these compounds was found to obey the Langmuir isotherm. The effect of temperature on the rate of corrosion in the absence and presence of these compounds was also studied. Some activated thermodynamic parameters were calculated.

Int. J. Corros. Scale Inhib., , 2, 82-91 PDF (801 K)
doi: 10.17675/2305-6894-2013-2-2-082-091

A new approach to resolve problems in the corrosion protection of metals

  • ,
OOO NPO NEPhTEKhIM, ul. Pulkovskaya 10, St. Petersburg, 196158 Russian Federation

Abstract: It has been shown that corrosion damage of equipment at an oil refinery plant as a common organism is determined by the combined effect of the process media at all stages of operation. Corrosion charts of units have been composed. Methods for the protection of oil refinery plant equipment from local and downtime corrosion, issues of material selection for cladding of surfaces of vessels and pipelines, and an up-to-date scheme of inhibitor protection of oil processing units in operation have been discussed and proposed. A new approach to the choice of starting products and reactions for synthesizing versatile inhibitors of atmospheric corrosion is considered. A new versatile fungicide inhibitor, VNKh-L-408, has been synthesized using this approach.

Int. J. Corros. Scale Inhib., , 2, 92-101 PDF (862 K)
doi: 10.17675/2305-6894-2013-2-2-092-101

Material balance of corrosion inhibitors. Distribution at lab testing and field application

  • I. S. Sivokon
OJSC Transenergostroi, Derbenevskaya nab. 7, bldg. 10, Moscow, 115114 Russian Federation

Abstract: This article may produce an impression that it deals with low priority issues of pipelines corrosion inhibitor protection processes and corrosion inhibitors (CI) lab testing techniques. However, it is proved that clear understanding of CI active molecules location makes it possible to identify the causes of CI inefficiency and can be used to produce recommendations to adjust lab testing and CI efficiency evaluation techniques. Inadequate attention paid to the CI distribution material balance may result in:
– Wrong choice of CIs at lab tests
– Excessive or insufficient concentration selection to ensure required protective action at field applications
A series of recommendations is proposed by the author based on a discussion and review of the cases described in the article. Research guidelines are proposed as knowledge of CI properties is essential to overcome current shortcomings.

Int. J. Corros. Scale Inhib., , 2, 102-114 PDF (630 K)
doi: 10.17675/2305-6894-2013-2-2-102-114

Passivation of carbon steel in neutral chloride media by inhibited compositions based on normal alkanes

  • , ,
Derzhavin State University, ul. Internatsyonalnaya 33, Tambov, 392000 Russian Federation

Abstract: The cathodic and anodic polarization of steel electrodes covered by thin films of compositions containing a 10 wt.% mixture of amines of hydrogenated acids of tall oil or individual C16H33NH2 amine in n-C15H32 or n-C10H22 has been studied in 0.5 M NaCl solution. At the polarization from the cathodic region to the anodic one, a potential range is observed where the process rate does not depend on the potential. This potential range spreads in both directions from the corrosion potential and is interpreted as the non-oxide passivity region.

Int. J. Corros. Scale Inhib., , 2, 115-121 PDF (598 K)
doi: 10.17675/2305-6894-2013-2-2-115-121

Anodic behavior of aluminum in α-alanine aqueous solutions at various pH values

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russian Federation

Abstract: The effect of α-alanine on aluminum anodic behavior in its solutions with pH values from 4.2 to 8.5 has been studied. It has been found that, depending on the pH, the amino acid exhibits a dual effect. On the one hand, α-alanine zwitter-ions (pH 4.2–5.6) behaving like an inhibitor slow down the anodic process, so aluminum is in a stable passive state at these pH values in the vicinity of the isoelectric point of the amino acid. The probable reason of the observed effect is that strong intermolecular hydrogen bridges that are formed between the amino and carboxy groups in the amino acid zwitter-ions predominate over interactions with the oxidized aluminum surface. On the other hand, it has been shown that the α-alanine anions formed at pH = 8.5 stimulate pit formation on aluminum surface in these solutions. Based on literature and experimental data, a dissociative mechanism of pit formation on aluminum in the systems in question is suggested.

Int. J. Corros. Scale Inhib., , 2, 122-131 PDF (886 K)
doi: 10.17675/2305-6894-2013-2-2-122-131

Benzotriazole as an inhibitor of the anodic dissolution of cadmium, bismuth, and their eutectic alloy in a neutral borate solution

  • ,
Southern Federal University, ul. Zorge 7, Rostov-on-Don, 344090 Russian Federation

Abstract: The electrochemical behavior of an eutectic cadmium-bismuth alloy in borate buffer solution containing 1,2,3-benzotriazole (BTA) as an additive has been studied. The additive inhibits the cadmium and alloy dissolution to an appreciable extent. It has been shown that the experimental polarization curve of the alloy is similar to that calculated based on the additive scheme. However, the currents on the experimental curve are lower due to selective mode of cadmium dissolution from the alloy. The kinetics of passive film formation was also studied.

Int. J. Corros. Scale Inhib., , 2, 132-137 PDF (783 K)
doi: 10.17675/2305-6894-2013-2-2-132-137

Protective effects of some anionic surfactants on an Ag-containing aluminium alloy (AA2139). Comparison with the action on a Li-containing aluminium alloy (AA2198)

  • , ,
Corrosion and Metallurgy Study Centre “A. Daccò”, Engineering Department, University of Ferrara, v. G. Saragat 4a, 44122, Ferrara (I)

Abstract: The influence exerted by some anionic surfactants towards the corrosion process of an Ag-containing aluminium alloy (AA2139) is studied during 168 h immersion in 0.01 M NaCl solution. This behaviour is compared with that previously determined on a Li-containing alloy (AA2198). The surfactants, at a proper concentration, hinder anodic and cathodic reactions as well as the pitting process, but their action is influenced by passive layer stability, so that their inhibiting effects are greater on AA2198 for the more efficient and stable passive layer. On both alloys, the most efficient compounds are the sodium salts of N-lauroylsarcosine and of dodecylbenzensulphonic acid.

Int. J. Corros. Scale Inhib., , 2, 138-149 PDF (2 494 K)
doi: 10.17675/2305-6894-2013-2-2-138-149

Corrosion protection of tank product side bottoms

  • , , and
1 Northern Technologies International Corporation, 23205 Mercantile Rd., Beachwood OH 44122, USA
2 A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119071 Russian Federation
3 PETROBRAS, ZIP: 20031-170, Rio de Janeiro, RJ, Brazil

Abstract: Corrosion of storage tank product side bottoms and tanks of tankers is one of the most critical problems worldwide in oil and gas industry. The protection methods currently in use include cathodic protection systems (CPS) and soluble corrosion inhibitors (SCI). Crude oils contain water and various soluble inorganic and organic compounds. During the storage and transportation of crude oil, the sediment aqueous solutions (SAS) contains high concentrations of H2S, Cl, SO42-, etc. The corrosion rates of storage tanks and tanks of tanker bottoms can vary from 0.05 to 3.0 mm per year. The service life of tank bottoms is unpredictable and can range from 2 to 20 years. In many cases, traditional corrosion protection systems (cathodic protection, coatings, and inhibitors) are not efficient enough, have short service life, or cannot be applied. This paper describes a new multistage corrosion protection system that combines different types of soluble corrosion inhibitors and cathodic protection systems. Together they achieve synergistic effects that can decrease the inhibitor protection concentration 3- to 6-fold and the current density 2- to 5-fold. This results in an increased service life of the corrosion protection method.

Int. J. Corros. Scale Inhib., , 2, 150-161 PDF (738 K)
doi: 10.17675/2305-6894-2013-2-2-150-161

Prev. issue<- -> Next issue