Flow Accelerated Corrosion of Carbon Steel with Droplet Impingement Using a Modified Rotating Cylinder Electrode Experiment

CORROSION ◽  
10.5006/3345 ◽  
2020 ◽  
Vol 76 (2) ◽  
pp. 202-209 ◽  
Author(s):  
Amna Esayah ◽  
Madison Kelley ◽  
Andrew Howell ◽  
Stephen J. Shulder ◽  
Brajendra Mishra ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Rotating Cylinder ◽  
Liquid Films ◽  
Electrode System ◽  
Carbon Steels ◽  
Protective Oxide ◽  
Droplet Impingement ◽  
Accelerated Corrosion ◽  
Rotating Cylinder Electrode ◽  
Flow Accelerated Corrosion

In power plant cooling systems, water droplets and condensate films form due to heat transfer through cooling tube walls. Condensate films are known to cause flow accelerated corrosion on carbon steels used in air-cooled condensers. Corrosion is further accelerated by droplets suspended in the accelerating steam that impinge on walls, T-joints, or valves, further damaging protective oxide layers on pipe walls. Droplet impingement and flow accelerated corrosion were studied using a modified rotating cylinder electrode system coupled with electrochemical impedance spectroscopy. Surface liquid films caused by droplet impingement were found to correlate directly with flow accelerated corrosion caused by condensate films. In the absence of a stable liquid film, droplet impingement increased corrosion rates and resulted in pit formation. Select corrosion inhibitors were found to be ineffective under flow accelerated corrosion or droplet impingement.

Flow Accelerated Corrosion Behavior of CANDU Feeder Piping Characterized by High Temperature Rotating Cylinder Electrode

2002 ◽  
Author(s):  
Jun Hwan Kim ◽  
In Sup Kim ◽  
Han Sub Chung
Keyword(s):  
High Temperature ◽  
Water Environment ◽  
Rotating Cylinder ◽  
Stable Operation ◽  
Accelerated Corrosion ◽  
Rotating Cylinder Electrode ◽  
High Temperature Water ◽  
Working Electrode ◽  
Flow Accelerated Corrosion ◽  
Temperature Water

To test the flow accelerated corrosion in nuclear power plant environment with ease, High Temperature Rotating Cylinder Electrode (HTRCE) was developed. The main design concept of HTRCE is to assure stable operation of working electrode up to highest possible rotation speed in a severe environment, to insulate electrode housing except working electrode surface against external fluid, and to extract corrosion parameter from the rotating cylinder to outside of the autoclave safely. From the results of corrosion experiment at high temperature water, HTRCE has been proved as an effective device to evaluate the velocity sensitivity in high temperature water environment.

Effects of Cr Content and Environmental Factors on FAC Rate of Carbon Steels

2009 ◽  
Author(s):  
Yutaka Watanabe ◽  
Kiwamu Sue ◽  
Hiroshi Abe
Keyword(s):  
Environmental Factors ◽  
Removal Rate ◽  
Carbon Steels ◽  
Strong Impact ◽  
Oxide Compound ◽  
Accelerated Corrosion ◽  
Cr Content ◽  
Ph Dependency ◽  
Order Of Magnitude ◽  
Flow Accelerated Corrosion

Combined effects of Cr content and environmental factors, pH and dissolved oxygen concentration, on removal rate of carbon steels due to flow accelerated corrosion have been examined by experiments. The effects of environmental factors on FAC rate have been attempted to interpret based on oxide solubility, which has been precisely evaluated by separate experiments and numerical estimations. pH dependency of the FAC rate has been found to be directly related to solubility of magnetite. Cr content holds a strong impact on the FAC rate regardless of pH values from 6.84 to 10.4. Addition of 1% Cr to a carbon steel reduces the FAC rate by one order of magnitude under the environmental conditions, where magnetite forms. Addition of oxygen up to 1200ppb changes the oxide from magnetite to hematite, resulting in significant improvement in corrosion resistance. Oxide film characteristics, e.g. compositional distributions and types of oxide compound, have been also examined and their correlation to the FAC rate has been discussed.

scholarly journals Evaluation of Flow Accelerated Corrosion of Carbon Steel with Rotating Cylinder

2012 ◽  
Vol 11 (6) ◽  
pp. 257-262
Author(s):  
Tae Jun Park ◽  
Eun Hee Lee ◽  
Kyung Mo Kim ◽  
Hong Pyo Kim
Keyword(s):  
Carbon Steel ◽  
Rotating Cylinder ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion

Potential Difference Distribution on Flat Plate Around Semi-Ellipsoidal Thinning on the Back Surface

2014 ◽  
Author(s):  
Naoya Tada ◽  
Makoto Uchida ◽  
Manabu Nohara
Keyword(s):  
Flat Plate ◽  
Liquid Droplet ◽  
Potential Difference ◽  
Back Surface ◽  
Analysis Method ◽  
Droplet Impingement ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion ◽  
Non Destructive ◽  
Local Wall Thinning

Local wall thinning is one of serious problems in aged power generating plants and is known to occur mainly by Flow Accelerated Corrosion (FAC) and Liquid Droplet Impingement (LDI) erosion. As the thinning grows inside the pipes, it is difficult to detect and evaluate it from the outer surface of pipe. The direct-current potential difference method (DC-PDM) is thought to be a suitable non-destructive technique to monitor the initiation and growth of these damages. In this study, an approximate analysis method of the potential difference around a semi-ellipsoidal thinning on the back surface of flat plate is presented and the accuracy is discussed based on the results obtained by the finite element analyses.

Studies on Flow and Pipe Wall Thinning and the Reduction in the Downstream of Orifice Nozzle

2011 ◽  
Author(s):  
Toshihiko Shakouchi ◽  
Takayuki Suzuki ◽  
Hideki Yuya ◽  
Masaki Naruse ◽  
Koichi Tsujimoto ◽  
...  
Keyword(s):  
Cavitation Erosion ◽  
Pipe Wall ◽  
Liquid Droplet ◽  
Piping System ◽  
Droplet Impingement ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
System 1 ◽  
Flow Accelerated Corrosion ◽  
Droplet Impingement Erosion

In a piping system of power plant, pipe wall thinning by Flow Accelerated Corrosion, FAC, Liquid Droplet Impingement Erosion, LDI, and Cavitation Erosion, C/E, are very serious problems because they give a damage and lead to the destructtion of the piping system[1]–[6]. In this study, the pipe wall thinning by FAC in the downstream of orifice nozzle, flow meter, is examined. Namely, the characteristics of FAC, generation mechanism, and prediction of the thinning and the reduction are made clear by experimental analysis. As a results, it was made clear that (1) the thinning is occurred mainly according to the size of the pressure fluctuation p′ on the pipe wall and the thinning can be estimated by it, and (2) the suppression of p′ can be realized by replacing the orifice to a taper shaped one having an angle to the upstream.

Effect of Material Factors on FAC Rate and Characteristics of Oxide Layer

2010 ◽  
Author(s):  
Yutaka Watanabe ◽  
Hiroshi Abe ◽  
Takamichi Miyazaki
Keyword(s):  
Oxide Layer ◽  
Defect Density ◽  
Carbon Steels ◽  
Metal Interface ◽  
Accelerated Corrosion ◽  
Cr Content ◽  
Transmission Electron ◽  
Scale Characteristics ◽  
Cr Concentration ◽  
Flow Accelerated Corrosion

Combined effects of Cr content and pH on corrosion rate of carbon steels due to flow accelerated corrosion have been examined by experiments and their relation to oxide scale characteristics based on detailed oxide layer characterizations using transmission electron microscope with X-ray analyzer have been discussed. Effect of Cr content on FAC mitigation decrease continuously as pH is increased from neutral to 10.4 and effect of pH on that increase significantly from pH 9.1 to 9.4. Obvious Cr enrichment has been observed in the oxide layer of 1.01 wt% Cr content steel regardless pH condition. Cr concentration is highest at top surface of oxide layer, and that decrease from surface to oxide / metal interface gradually. It has been suggested that Cr enrichment stabilize oxide layer (decrease solubility and defect density of oxide layer), as a result, FAC suppressed.

Tackling Erosion in Nuclear Piping Systems

2007 ◽  
Author(s):  
Harold M. Crockett ◽  
Jeffrey S. Horowitz
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Training Module ◽  
Droplet Impingement ◽  
Damage Mechanisms ◽  
Accelerated Corrosion ◽  
Computerized Training ◽  
Piping Systems ◽  
Research Plan ◽  
Flow Accelerated Corrosion

Various mechanisms degrade power piping in nuclear power plants. The most important mechanism has been flow-accelerated corrosion (FAC). FAC has caused ruptures and leaks and has led to numerous piping replacements. U.S. utilities are using a combination of EPRI software and aggressive inspection programs to deal with FAC. However, current technology does not deal with erosive forms of attack including, cavitation erosion, flashing erosion, droplet impingement, and solid particle erosion. These forms of degradation have caused shutdowns and leaks have become a maintenance issue. To deal with these problems EPRI has begun a series of projects in this area. The first of these was a comprehensive report on erosion in piping systems. This work was followed with a computerized training module designed to educate utility engineers about erosive attack. Further steps are planned to deal with these forms of degradation. The first will be a meeting with knowledgeable EPRI and utility engineers to prioritize the damage mechanisms. From this meeting a research plan will be developed. This paper will present a description of erosive damage mechanisms and describe the planned R&D to deal with these mechanisms.

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