scholarly journals C206 Prediction trend of existing evaluation method of wall thinning rate caused by flow accelerated corrosion in two phase flow

2011 ◽  
Vol 2011.16 (0) ◽  
pp. 299-300
Author(s):  
Masaaki SATAKE ◽  
Kimitoshi Yoneda ◽  
Fumio Inada
Keyword(s):  
Evaluation Method ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Flow Accelerated Corrosion ◽  
Thinning Rate

Proposal of the Estimation Equation of Flow Accelerated Corrosion Under Water-Steam Two-Phase Flow

2013 ◽  
Author(s):  
Masaaki Satake ◽  
Kimitoshi Yoneda ◽  
Ryo Morita ◽  
Fumio Inada
Keyword(s):  
Flow Condition ◽  
Two Phase Flow ◽  
Pipe Wall ◽  
Prediction Equation ◽  
Phase Flow ◽  
Two Phase ◽  
Accelerated Corrosion ◽  
Water Steam ◽  
Flow Accelerated Corrosion ◽  
Thinning Rate

Flow accelerated corrosion (FAC) is one of the pipe wall thinning phenomena. There are a few prediction equations for FAC under the two-phase flow condition, but their accuracy is uncertain. In this study, these equations are summarized. A new prediction equation is proposed, in which the liquid film velocity near the wall is taken into account. Also, FAC experiments with water-steam two-phase flow are performed. The thinning rate is predicted by calculation and compared with the experimental value.

Experimental investigation of flow accelerated corrosion under two-phase flow conditions

2014 ◽  
Vol 267 ◽  
pp. 34-43 ◽  
Author(s):  
Wael H. Ahmed ◽  
Mufatiu M. Bello ◽  
Meamer El Nakla ◽  
Abdelsalam Al Sarkhi ◽  
Hassan M. Badr
Keyword(s):  
Experimental Investigation ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion

Effect of Ethanolamine, Ammonia, Acetic Acid, and Formic Acid on Two-Phase Flow Accelerated Corrosion in Steam–Water Cycles

2015 ◽  
Vol 54 (36) ◽  
pp. 8963-8970 ◽  
Author(s):  
D. H. Moed ◽  
S. Weerakul ◽  
D. H. Lister ◽  
N. Leaukosol ◽  
L. C. Rietveld ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Accelerated Corrosion ◽  
Flow Accelerated Corrosion ◽  
Water Cycles

Techniques for Improved Reliability of Wall Thinning Estimation

2006 ◽  
Author(s):  
Yogendra S. Garud
Keyword(s):  
The Other ◽  
Remaining Life ◽  
Data Filtering ◽  
Large Database ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Simplified Method ◽  
Flow Accelerated Corrosion ◽  
The Impact ◽  
Thinning Rate

Wall thinning in pressure retaining components, especially due to the flow-accelerated corrosion, has been a significant factor affecting the safety and unplanned system downtimes. On the other hand, overestimating the impact of possible wall thinning often leads to unnecessary or expensive inspections and replacements. The simplified or quick (short-cut) methods of analysis and prediction often lack the requisite degree of accuracy and confidence. This paper presents a few techniques for better analysis of the wall thinning data to address these issues. These techniques make use of the statistical methods, pattern recognition, and optimization to perform a robust data filtering and thinning rate estimation that accounts for measurement uncertainty. The techniques are discussed with application to a large database and an inspection program. The impact of these analytical improvements is presented in comparison with results of the simplified method of analysis. The results include both the margin on remaining life and the projected wall thinning rates, with implications for inspections.

Numerical Calculation of Shear Stress Distribution on the Inner Wall Surface of CANDU Reactor Feeder Pipe Conveying Two-Phase Coolant

2007 ◽  
Author(s):  
Jong Chull Jo ◽  
Dong Gu Kang ◽  
Kyung Wan Roh
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Wall Thickness ◽  
Shear Stress Distribution ◽  
Cfd Analysis ◽  
Two Phase ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Local Areas ◽  
Flow Accelerated Corrosion

Two-phase flow fields inside feeder pipes of a CANDU reactor have been simulated numerically using a CFD (computational fluid dynamics) code to calculate the shear stress distribution which is the most important factor to be considered in predicting the local areas of feeder pipes highly susceptible to FAC (flow-accelerated corrosion)-induced wall thinning. The CFD approach with schemes used in this study to simulate the turbulent flow situations inside the CANDU feeder pipes had been verified by showing a good agreement between the investigation results for the failed feedwater pipe at Surry Unit 2 plant in U.S. and the CFD calculation. Sensitivity studies of the three geometrical parameters such as angle of the 1st and 2nd bends, length of the 1st span between the grayloc hub and the 1st bend, and length of the 2nd span between the 1st and the 2nd bends had already been performed. In this study, the effects of void fraction of the primary coolant coming out from the exit of pressure tubes containing nuclear fuels on the fluid shear stress distribution at the inner surface of feeder pipe wall have been investigated to find out the local areas of feeder pipes conveying two-phase coolant, where are highly susceptible to FAC (flow-accelerated corrosion)-induced wall thinning. As the results of CFD analysis, it is seen that the local regions of feeder pipes of the operating CANDU reactors in Korea, on which the wall thickness measurements have been performed so far, are not coincided with the worst regions predicted by the present CFD analysis where is the connection region of straight & bend pipe near the inlet part of the bend intrados. Finally, based on the results of the present CFD analysis a guide to the selection of the weakest local positions where the measurement of wall thickness should be performed with higher priority has been provided.

Evaluation of Wall Thinning Rate Due to Flow Accelerated Corrosion With the Coupled Models of Electrochemical Analysis and Double Oxide Layer Analysis

2009 ◽  
Author(s):  
Masanori Naitoh ◽  
Shunsuke Uchida ◽  
Yasushi Uehara ◽  
Hidetoshi Okada ◽  
Seiichi Koshizuka
Keyword(s):  
Oxide Layer ◽  
Electrochemical Analysis ◽  
Anodic Current Density ◽  
Coupled Models ◽  
Accelerated Corrosion ◽  
Double Oxide ◽  
Wall Thinning ◽  
Layer Analysis ◽  
Flow Accelerated Corrosion ◽  
Thinning Rate

Systematic approaches for evaluating flow accelerated corrosion (FAC) are desired before discussing application of countermeasures for FAC. Future FAC occurrence should be evaluated to identify locations where a higher possibility of FAC occurrence exists, and then, wall thinning rate at the identified FAC occurrence zone should be evaluated to obtain the preparation time for applying countermeasures. Wall thinning rates were calculated with the coupled models of static electrochemical analysis and dynamic double oxide layer analysis. Anodic current density and electrochemical corrosion potential (ECP) were calculated with the electrochemistry model based on an Evans diagram and ferrous ion release rate determined by the anodic current density was applied as input for the double oxide layer model. The thickness of oxide layer was calculated with the double oxide layer model. The dependences of mass transfer coefficients, oxygen concentrations ([O2]), pH and temperature on wall thinning rates were calculated with the coupled model. It was confirmed that the calculated results of the coupled models resulted good agreement with the measured ones. The effects of candidates for countermeasures, e.g., optimization of N2H4 injection point into the feed water system, on FAC mitigation was demonstrated as a result of applying the model.

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