scholarly journals Comprehensive investigation of the corrosion state and surface properties of the stainless steel tubes of steam generators

2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Andrea Szabó Nagy ◽  
Kálmán Varga ◽  
Bernadett Baja ◽  
Zoltán Németh ◽  
Deszo Oravetz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Heat Exchanger ◽  
Chemical Composition ◽  
Oxide Layer ◽  
General Corrosion ◽  
Steam Generators ◽  
Protective Oxide ◽  
Comprehensive Investigation ◽  
Protective Oxide Layer ◽  
Corrosion State

Evaluating the water chemistry in the primary circuit and the effect of chemical econtamination of the heat exchanger tubes performed by the AP-CITROX (AP: alkaline permanganate; CITROX: citric and oxalic acid) procedure at Paks NPP (Hungary), a project dealing with the comprehensive investigation of the general corrosion state of the steam generators (SGs) has been initiated. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research program based on sampling as well as on ex-situ electrochemical (voltammetric) and surface analytical measurements (SEM-EDX, CEMS, XRD, XPS) was developed and elaborated. In the time period of 2000-2008 - within the frame of the above project - 45 stainless steel specimens, cut out from various locations of the steam generators of the Paks NPP were investigated. Based on the measured corrosion characteristics (corrosion rate, thickness and chemical composition of the protective oxide-layer) it was found that these parameters are strongly dependent on the decontamination history of steam generators. The present work gives a brief overview on the general corrosion state of the heat exchanger tubes of SGs, concerning the long-term effects of the AP-CITROX procedure on the chemical composition and structure of the protective oxide-layer.

scholarly journals Long-term effects of a chemical decontamination procedure on the corrosion state of the heat exchanger tubes of steam generators

2022 ◽  
Vol 7 (1) ◽  
pp. 77-83
Author(s):  
Andrea Szabó Nagy ◽  
Kálmán Varga ◽  
Bernadett Baja ◽  
Zoltán Németh ◽  
Desző Oravetz ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Heat Exchanger ◽  
Oxide Layer ◽  
In Situ Monitoring ◽  
Ex Situ ◽  
General Corrosion ◽  
Long Term Effects ◽  
Steam Generators ◽  
Corrosion State

Our previous studies have revealed that a ”hybrid” structure of the amorphous and crystalline phases is formed in the outermost surface region of the austenitic stainless steel tubes of steam generators (SGs) as an undesired consequence of the industrial application of the AP-CITROX (AP: alkaline permanganate; CITROX: citric and oxalic acid) decontamination technology. The formation of this mobile oxide-layer increased the amount of the corrosion products in the primary circuit significantly, resulting in magnetite deposition on fuel assemblies. Owing to the fact that there is no investigation method available for the in-situ monitoring of the inner surfaces of heat exchanger tubes, a research project based on sampling as well as on ex-situ electrochemical and surface analytical measurements was elaborated. Within the frame of this project, comprehensive investigation of the general corrosion state and metallographic features of 36 stainless steel specimens, cut out from various locations of the 21 steam generators of the Paks NPP in the time period of 2000-2007 has been performed. The present work gives a brief overview on the general corrosion state of the heat exchanger tubes of SGs, concerning the long-term effects of the AP-CITROX procedure on the chemical composition and structure of the protective oxide-layer.

Comprehensive investigation of the corrosion state of the heat exchanger tubes of steam generators

2007 ◽  
pp. 289-305 ◽  
Author(s):  
K. Varga ◽  
Z. Németh ◽  
A. Szabó ◽  
K. Radó ◽  
D. Oravetz ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Steam Generators ◽  
Comprehensive Investigation ◽  
Corrosion State

Effect of a chemical decontamination procedure on the corrosion state of the heat exchanger tubes of steam generators

2006 ◽  
Vol 48 (9) ◽  
pp. 2727-2749 ◽  
Author(s):  
A. Szabó ◽  
K. Varga ◽  
Z. Németh ◽  
K. Radó ◽  
D. Oravetz ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Steam Generators ◽  
Chemical Decontamination ◽  
Corrosion State

Nanoporous anodic alumina obtained without protective oxide layer by hard anodization

2012 ◽  
Vol 67 (1) ◽  
pp. 296-299 ◽  
Author(s):  
A. Santos ◽  
P. Formentín ◽  
J. Ferré-Borrull ◽  
J. Pallarès ◽  
L.F. Marsal
Keyword(s):  
Oxide Layer ◽  
Anodic Alumina ◽  
Protective Oxide ◽  
Protective Oxide Layer ◽  
Nanoporous Anodic Alumina

Selective exposure of platinum catalyst embedded in protective oxide layer on conductive titanium carbide support

2019 ◽  
Vol 13 ◽  
pp. 353-361
Author(s):  
Zishuai Zhang ◽  
Mohammad Amin Sadeghi ◽  
Nicolas Brodusch ◽  
Raynald Gauvin ◽  
Siyu Ye ◽  
...  
Keyword(s):  
Titanium Carbide ◽  
Oxide Layer ◽  
Platinum Catalyst ◽  
Selective Exposure ◽  
Protective Oxide ◽  
Protective Oxide Layer

Free fatty acid influenced corrosion inhibition mechanisms of some inedible plants seeds oils on low alloyed medium-carbon steel in H2SO4

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Olanrewaju Moses Adesusi ◽  
Olayide Rasaq Adetunji ◽  
Tunji John Erinle ◽  
Iliyasu Kayode Okediran ◽  
Olumide Olufunso Akinpelu ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Carbon Steel ◽  
Free Fatty Acid ◽  
Oxide Layer ◽  
Corrosion Inhibition ◽  
Medium Carbon Steel ◽  
Protective Oxide ◽  
Medium Carbon ◽  
Protective Oxide Layer ◽  
Content Type

Purpose The purpose of this paper is to investigate the mechanisms of low alloyed medium-carbon steel (LAMCS) corrosion in 0.5 M H2SO4 inhibited by seeds oils of rubber (SOR), Neem (SON) and Jatropha (SOJ) containing varying degree of free fatty acid (FFA). Design/methodology/approach Specific gravity, acid values and FFA compositions of oils were determined. Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) are techniques used to investigate the corrosion inhibition mechanisms with evaluated Gibbs free energy of adsorption. Findings Corrosion inhibition efficiencies of oils reached values >99% as obtained from PDP and EIS. Protective oxide layer was formed on LAMCS consequent on containment of carbonyl and hydroxyl groups in the FFA of SOR, SON and SOJ, respectively. The SOR and SOJ are found to be mixed inhibitors, whereas SON behaved as anodic inhibitor. Mechanism of adsorption of SOR was synergistic between physisorption and chemisorption, while SON and SOJ exhibited physisorption. SEM micrographs images showed that uninhibited sample exhibited thicker mass of corrosion products. Formation of protective oxide layer was confirmed by XRD diffractograms. Practical implications This study has shown that the need for modification of vegetable seed oils containing FFA is unnecessary as the hydroxyl and carbonyl groups of the FFA contained in the respective oil were found to be the center of adsorption of the oils on the steel surface. Hence, cost and by-products associated with modification of oils used as corrosion inhibitors are eliminated. Originality/value SOR, which has the highest percentage FFA, was found to be the most influential on the corrosion inhibition mechanism of LAMCS, specifically within 0.01–0.02 g/mL concentration. FFA contained in the respective seed oil aided formation of protective oxide layer at interface between H2SO4 and LAMCS, relative to amount composed.

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