• Title/Summary/Keyword: flow-accelerated corrosion

Search Result 120, Processing Time 0.173 seconds

Analysis of Flow-Accelerated Corrosion Effects by the Type of Orifice (오리피스 유형별 유동가속부식 영향 분석)

  • Hwang, Kyeong-Mo;Jin, Tae-Eun;Kim, Kyung-Hoon
    • Proceedings of the KSME Conference
    • /
    • 2008.11b
    • /
    • pp.2483-2488
    • /
    • 2008
  • To mitigate the effects of cavitation and flashing, several types of orifices have been installed in the pipeline of new nuclear power plants. To review the effects of wall thinning caused by flow-accelerated corrosion by the types of orifices, which are cone and plate, and the relation between flow behavior and local wall thinning, experiments and numerical analyses for the downstream pipe of two types of orifices were performed. The experimental results in terms of static pressure obtained for the experimental facilities were compared with those of three-dimensional (3D) numerical analyses using the FLUENT code. As the results of review of flow-accelerated corrosion effects based on the experiment and numerical analysis, it was identified that the orifice of cone-type can be comparatively mitigated the effects of cavitation and flashing, but can not be mitigated the effect of flow-accelerated corrosion.

  • PDF

Three-dimensional Turbulent Flow Analysis in Curved Piping Systems Susceptible to Flow-Accelerated Corrosion (유동가속부식이 잠재한 곡관내의 3차원 난류유동 해석)

  • Jo, Jong-Chull;Kim, Yun-Il;Choi, Seok-Ki
    • Proceedings of the KSME Conference
    • /
    • 2000.04a
    • /
    • pp.900-907
    • /
    • 2000
  • The three-dimensional turbulent flow in curved pipes susceptible to flow-accelerated corrosion has been analyzed numerically to predict the pressure and shear stress distributions on the inner surface of the pipes. The analysis employs the body-fitted non-orthogonal curvilinear coordinate system and a standard $ {\kappa}-{\varepsilon}$ turbulence model with wall function method. The finite volume method is used to discretize the governing equations. The convection term is approximated by a high-resolution and bounded discretization scheme. The cell-centered, non-staggered grid arrangement is adopted and the resulting checkerboard pressure oscillation is prevented by the application of a modified version of momentum interpolation scheme. The SIMPLE algorithm is employed for the pressure and velocity coupling. The numerical calculations have been performed for two curved pipes with different bend angles and curvature radii, and discussions have been made on the distributions of the primary and secondary flow velocities, pressure and shear stress on the inner surface of the pipe to examine applicability of the present analysis method. As the result it is seen that the method is effective to predict the susceptible systems or their local areas where the fluid velocity or local turbulence is so high that the structural integrity can be threatened by wall thinning degradation due to flow-accelerated corrosion.

  • PDF

High-temperature ultrasonic thickness monitoring for pipe thinning in a flow-accelerated corrosion proof test facility

  • Cheong, Yong-Moo;Kim, Kyung-Mo;Kim, Dong-Jin
    • Nuclear Engineering and Technology
    • /
    • v.49 no.7
    • /
    • pp.1463-1471
    • /
    • 2017
  • In order to monitor the pipe thinning caused by flow-accelerated corrosion (FAC) that occurs in coolant piping systems, a shear horizontal ultrasonic pitch-catch waveguide technique was developed for accurate pipe wall thickness monitoring. A clamping device for dry coupling contact between the end of the waveguide and pipe surface was designed and fabricated. A computer program for multi-channel on-line monitoring of the pipe thickness at high temperature was also developed. Both a four-channel buffer rod pulse-echo type and a shear horizontal ultrasonic waveguide type for high-temperature thickness monitoring system were successfully installed to the test section of the FAC proof test facility. The overall measurement error can be estimated as ${\pm}10{\mu}m$ during a cycle from room temperature to $200^{\circ}C$.

A Numerical Study on Flow-Accelerated Corrosion in Two Adjacent Elbows

  • Yun, Hun;Hwang, Kyeongmo;Moon, Seung-Jae
    • Corrosion Science and Technology
    • /
    • v.15 no.1
    • /
    • pp.6-12
    • /
    • 2016
  • Flow-Accelerated Corrosion (FAC) is a well-known degradation mechanism that attacks the secondary piping in nuclear power plants. Since the Surry Unit 2 event in 1986, most nuclear power plants have implemented management programs to deal with damages in carbon and low-alloy steel piping. Despite the utmost efforts, damage induced by FAC still occurs in power plants around the world. In order to predict FAC wear, some computer programs were developed such as CHECWORKS, CICERO, and COMSY. Various data need to be input to these programs; the chemical composition of secondary piping, flow operating conditions and piping geometries. CHECWORKS, developed by the Electric Power Research Institute (EPRI), uses a geometry code to calculate geometry effects. Such a relatively simple geometry code is limited in acquiring the accuracy of FAC prediction. Recently, EPRI revisited the geometry code with the intention of updating it. In this study, numerical simulations were performed for two adjacent $90^{\circ}$ elbows and the results were analysed in terms of the proximity effect between the two adjacent elbows.

Flow-Accelerated Corrosion Behavior of SA106 Gr.C Steel in Alkaline Solution Characterized by Rotating Cylinder Electrode

  • Kim, Jun-Hwan;Kim, In-Sup
    • Nuclear Engineering and Technology
    • /
    • v.32 no.6
    • /
    • pp.595-604
    • /
    • 2000
  • Flow-Accelerated Corrosion Behavior of SA106 Gr.C steel in room temperature alkaline solution simulating the CANDU primary water condition was studied using Rotating Cylinder Electrode. Systems of RCE were set up and electrochemical parameters were applied at various rotating speeds. Corrosion current density decreased up to pH 10.4 then it increased rapidly at higher pH. This is due to the increasing tendency of cathodic and anodic exchange half-cell current. Corrosion potential shifted slightly upward with rotating velocity. Passive film was formed from pH 9.8 by the mechanism of step oxidation and the subsequent precipitation of ferrous species into hydroxyl compound. Above pH 10.4, the film formation process was active and the film became stable. Corrosion current density showed increment in pH 6.98 with the rotating velocity, while it soon saturated from 1000 rpm above pH 9.8. This seems that activation process which represents formation of passive film on the bare metal surface controls the entire corrosion process

  • PDF

Electrochemical Analysis on Flow-Accelerated Corrosion Behavior of SA106 Gr.C Steel in Alkaline Solution

  • Kim, Jun Hwan;Kim, In Sup;Chung, Han Sub
    • Corrosion Science and Technology
    • /
    • v.2 no.1
    • /
    • pp.41-46
    • /
    • 2003
  • Flow-Accelerated Corrosion behavior concerning both activation and mass transfer process of SA106 Gr.C steel was studied using rotating cylinder electrode in room temperature alkaline solution by DC and AC electrochemical techniques. Passive film was tanned from pH 9.8 by step oxidation of ferrous product into hydroxyl compound. Corrosion potential shifted slightly upward with rotating velocity through the diffusion of cathodic species. Corrosion current density increased with rotating velocity in pH 6.98, while it soon saturated from 1000 rpm at above pH 9.8. On the other hand the limiting current increased with rotating speed regardless of pH values. It seems that activation process, which represents formation of passive film on the bare metal surface, controls the entire corrosion kinetics

A Study on Prediction of Metal Loss by Flow-Accelerated Corrosion in the CANDU NPP Secondary Piping Systems (침부식에 의한 CANDU형 원전 2차측 배관의 감육 예측에 관한 연구)

  • Shim, S.H.;Song, J.S.;Yoon, K.B.;Hwang, K.M.;Jin, T.E.;Lee, S.H.;Kim, W.S.
    • Proceedings of the KSME Conference
    • /
    • 2001.06a
    • /
    • pp.616-621
    • /
    • 2001
  • Flow-accelerated corrosion(FAC) is a phenomenon that results in metal loss from piping, vessels, and equipment made of carbon steel. FAC occurs only under certain conditions of flow, chemistry, geometry, and material. Unfortunately, those conditions are in much of the high-energy piping in nuclear and fossil-fueled power plants. Also, for domestic NPP secondary pipings whose operating time become longer, more evidences of FAC have been reported. The authors are studying on FAC management using CHECWORKS, computer code developed by EPRI. This paper is on the prediction results of metal loss by FAC in the one of CANDU type NPP secondary piping systems.

  • PDF

A Study on Flow-Accelerated Corrosion of SA106 Gr.C Weldment (SA106 Gr.C강 용접재에서의 유체가속부식(FAC) 현상 연구)

  • Zheng Yugui
    • Journal of Welding and Joining
    • /
    • v.19 no.3
    • /
    • pp.334-341
    • /
    • 2001
  • The chemical and geometric effects of weld on flow-accelerated corrosion (FAC) of SA106 Gr.C low alloy steel pipe in 3.5wt% NaCl and simulated feedwater of nuclear power plant have been investigated by using rotating cylinder electrode. Polarization test and weight loss test were conducted and compared at rotating speed of 2000rpm (3.14m/s) with the variables of chemical and geometric parameters. The results showed that the chemical effects were relatively larger than the geometric effects, and the welded parts were the local anode and preferentially corroded, which could be explained by the differences between microstructural and compositional parameters. On the other hand, under active corrosion conditions, the heat affected zone were severely corroded and microstructural effects became the important role in the whole process.

  • PDF

A Study on the Relief of Shell Wall Thinning of Low Pressure Type Feedwater Heater Around the Extraction Nozzle Identified (저압형 급수가열기 추기노즐에서 동체 감육 완화에 관한 연구)

  • Kim, Kyung-Hoon;Hwang, Kyeong-Mo;Seo, Hyuk-Ki
    • Journal of ILASS-Korea
    • /
    • v.13 no.4
    • /
    • pp.173-179
    • /
    • 2008
  • The current machinery and tools of secondary channel of the nuclear power plants were produced in the carbon-steel and low-alloy steel. What produced with the carbon-steel occurs wall thinning effect from flow accelerated corrosion by the fluid flow at high temperature, high pressure. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle-installed. Wall thinning by flow accelerated corrosion occurs piping system, the heat exchanger, steam condenser and feedwater heaters etc,. Feedwater heaters of many nuclear power plants have recently experienced sever wall thinning damage, which will increase as operating time progress. This study describes the comparisons between the numerical results using the FLUENT code and experimental data of down scale model.

  • PDF