Pitting corrosion of steel tubes in an air preheater

2002 ◽  
Vol 2 (5) ◽  
pp. 67-73
Author(s):  
B. Vamsi Krishna ◽  
R. K. Sidhu
Keyword(s):  
Pitting Corrosion ◽  
Steel Tubes ◽  
Air Preheater ◽  
Corrosion Of Steel

Experimental Study of Propagation Stage of Pitting Corrosion of 20Cr13 Steel

2008 ◽  
Vol 38 ◽  
pp. 238-247
Author(s):  
A.D. Davydov ◽  
V.S. Shaldaev
Keyword(s):  
Pitting Corrosion ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Ph Value ◽  
Open Circuit ◽  
Effect Of Temperature ◽  
Pitting Potential ◽  
Free Corrosion Potential ◽  
External Power Source ◽  
Corrosion Of Steel

The initiation and development of pitting corrosion of steel 20Cr13 in the NaCl solutions with various concentrations, temperatures, and pH values are studied under the potentiostatic conditions and at the free-corrosion potential. The pitting and repassivation potentials are determined using the method of cycling voltammetry. In spite of the fact that thus determined pitting potential is more positive than the corrosion potential (the open-circuit potential Eo.c.), the long-term experiments, which were performed at the free-corrosion potential, showed that pitting corrosion takes place without imposing a potential using an external power source. It is concluded that the probability of pitting corrosion of steel should be determined by comparing the corrosion potential (the open-circuit potential) with the repassivation potential Erp. Steel 20Cr13 is prone to the pitting corrosion, because Erp is more negative than Eo.c.. In the potentiostatic experiments, the variation of the depth and diameter of pits and their number with the time and the effect of temperature and electrode rotation on the pit propagation are studied. The results, which were obtained at the free-corrosion potential, are much less reproducible. In this case, in contrast to the potentiostatic conditions, the pit depth increased only slightly and the pit width increased to a larger extent. The effect of concentration, pH value, and temperature of NaCl solutions on the pit propagation is considered. It is concluded that the data on the development of pitting corrosion under the potentiostatic conditions can be hardly extended to the conditions of free corrosion potential.

scholarly journals Direct and Indirect Evidence of the Microbially Induced Pitting Corrosion of Steel Structures in Humid Environments

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 983
Author(s):  
Jingzhong Zhou ◽  
Kuoteng Sun ◽  
Songqiang Huang ◽  
Xuemin He ◽  
Zhaowei Hu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Biofilm Formation ◽  
Indirect Evidence ◽  
Steel Structures ◽  
Electrochemical Analysis ◽  
Bacterial Biofilm ◽  
Direct Role ◽  
Severe Problem ◽  
Corrosion Of Steel

Corrosion is a severe problem for steel structures in humid environments. In particular, humidity usually triggers the surface adhesion of microorganisms, leading to microbiologically induced corrosion. This study aims to explore the effect of bacterial biofilm formation on the pitting corrosion of stainless steel. This research uses electrochemical methods to obtain indirect evidence of the pitting corrosion of steel. In addition, in order to obtain direct evidence of the pitting corrosion of stainless steel, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to characterize the dimensional morphology of the stainless steel after pitting. It was shown that the bacterial adhesion increased with the pH and temperature, which significantly increased the surface roughness of the stainless steel. Electrochemical analysis revealed that the formation of biofilm greatly destroyed the oxide film of 304 SS and accelerated the corrosion of stainless steel by forming an oxygen concentration battery. SEM and AFM analyses showed cracks and dislocations on the surface of stainless steel underneath the attached bacteria, which suggested a direct role of biofilm in corrosion induction. The results presented here show that the bacterial biofilm formation on the steel surfaces significantly accelerated the corrosion and affected the pitting corrosion process of the steel structure.

Pitting Corrosion of Steel in H2S Solutions

CORROSION ◽  
1976 ◽  
Vol 32 (2) ◽  
pp. 64-68 ◽  
Author(s):  
L. M. DVORACEK
Keyword(s):  
Pitting Corrosion ◽  
Corrosion Of Steel

Investigation of chloride-induced pitting corrosion of steel in concrete with innovative methods

2016 ◽  
Vol 67 (6) ◽  
pp. 583-590 ◽  
Author(s):  
G. Ebell ◽  
A. Burkert ◽  
J. Fischer ◽  
J. Lehmann ◽  
T. Müller ◽  
...  
Keyword(s):  
Pitting Corrosion ◽  
Innovative Methods ◽  
Corrosion Of Steel
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