Heat Exchanger Tube Fretting Wear: Review and Application to Design

1985 ◽  
Vol 107 (2) ◽  
pp. 149-156 ◽  
Author(s):  
P. L. Ko
Keyword(s):  
Heat Exchanger ◽  
Impact Force ◽  
Design Criterion ◽  
Fretting Wear ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
Dynamic Interactions ◽  
Tube Life ◽  
The Impact

Flow-induced vibration in steam generators and heat exchangers can cause dynamic interactions between tubes and tube supports resulting in fretting-wear. The effects on tube wear of various parameters, such as tube/support interactions, materials, and tube/support clearances have been studied. Techniques to predict the dynamic tube/support interaction and analyze the impact force at the support have been developed. The results of this work are reviewed and discussed in the context of how best they may be applied in the assessment of heat exchanger designs. A new design criterion based on support impact force is also discussed. Finally, a technique to predict long-term tube life is outlined.

EXPERIMENTAL STUDY ON IMPACT FRETTING WEAR OF INCONEL TUBES UNDER HIGH TEMPERATURE AND PRESSURE

2011 ◽  
Vol 25 (31) ◽  
pp. 4253-4256 ◽  
Author(s):  
CHOON YEOL LEE ◽  
JOON WOO BAE ◽  
YOUNG SUCK CHAI ◽  
KYOOSIK SHIN
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Impact Force ◽  
Fretting Wear ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
Experimental Parameters ◽  
Generator Design ◽  
The Impact

In nuclear power plant, fretting wear caused by flow induced vibration (FIV) accompanied with impact force can make serious problems between U -tubes and egg-crates which are located in steam generators. In order to guarantee the reliability of the steam generator, design based on consideration of the damage due to the fretting wear of the U -tube is inevitable. The purpose of this study is to elucidate fretting wear mechanism qualitatively and quantitatively. First, finite element models are developed to analyze the dynamic characteristics and estimate the impact force in steam generators. Based on the numerical results, fretting wear simulation is performed according to the environment to which the actual steam generators in nuclear power plant are exposed. Initial experimental results are obtained for various experimental parameters and the effect of work rate and temperature on fretting wear is evaluated.

Correlation of Support Impact Force and Fretting-Wear for a Heat Exchanger Tube

1984 ◽  
Vol 106 (1) ◽  
pp. 69-77 ◽  
Author(s):  
P. L. Ko ◽  
H. Basista
Keyword(s):  
Heat Exchanger ◽  
Impact Force ◽  
Computer Code ◽  
Oblique Impact ◽  
Dynamic Interaction ◽  
Fretting Wear ◽  
Heat Exchanger Tube ◽  
Dynamic Interactions ◽  
Realistic Assessment ◽  
Exchanger Tube

Flow-induced tube vibration can cause dynamic interactions between a tube and its supports. Both wear information and results from vibration analyses are needed to achieve a realistic assessment of long-term tube wear. Normal and oblique impact forces at the tube supports characterize dynamic interaction between tube and tube-support, and can be correlated to the rate of fretting-wear. A statistical analysis of the force signal provides an indication of the time distribution of various force levels during a vibration cycle. Different schemes for obtaining a weighted sum of these force levels were developed to account for changes in excitation levels, tube/support clearance, and the type of tube motion. With one of the schemes, the correlation to measured wear data was good. Therefore, fretting-wear can be estimated directly from the analytically predicted support impact force in a steam generator or heat exchanger tube. The effects of other support parameters, such as tube support land area, can be added to the empirical equation. A series of tests involving the three parameters mentioned were performed in room temperature water. Forces along two orthogonal axes at the support were recorded and analysed. The paper presents the results of these tests and shows the correlation between the wear results and the force functions. A computer code for predicting tube/support dynamic interaction is used to estimate wear damages from the experimental force-wear correlation.

Probabilistic Assessment of Fretting Wear in Steam Generator Tubes Under Flow Induced Vibrations

2003 ◽  
Author(s):  
Greg D. Morandin ◽  
Richard G. Sauve´
Keyword(s):  
Steam Generator ◽  
Degradation Mechanism ◽  
Probabilistic Methods ◽  
Fretting Wear ◽  
Nonlinear Flow ◽  
Impact Wear ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
Wear Damage ◽  
The Impact

Successful life management of steam generators requires an ongoing operational assessment plan to monitor and address all potential degradation mechanisms. A degradation mechanism of concern is tube fretting as a result of flow-induced vibration. Flow induced vibration predictive methods routinely used for design purposes are based on deterministic nonlinear structural analysis techniques. In previous work, the authors have proposed the application of probabilistic techniques to better understand and assess the risk associated with operating power generating stations that have aging re-circulating steam generators. Probabilistic methods are better suited to address the variability of the parameters in operating steam generators, e.g., flow regime, support clearances, manufacturing tolerances, tube to support interactions, and material properties. In this work, an application of a Monte Carlo simulation to predict the propensity for fretting wear in an operating re-circulation steam generator is described. Tube wear damage is evaluated under steady-state conditions using two wear damage correlation models based on the tube-to-support impact force time histories and work rates obtained from nonlinear flow induced vibration analyses. Review of the tube motion in the supports and the impact/sliding criterion shows that significant tube damage at the U-bend supports is a result of impact wear. The results of this work provide the upper bound predictions of wear damage in the steam generators. The EPRI wear correlations for sliding wear and impact wear indicate good agreement with the observed damage and, given the preponderance of wear sites subject to impact, should form the basis of future predictions.

An Experimental Investigation of the Dynamics of a Loosely Supported Tube Array

2017 ◽  
Author(s):  
Amro Elhelaly ◽  
Marwan Hassan ◽  
Atef Mohany ◽  
Soha Moussa
Keyword(s):  
Experimental Investigation ◽  
Impact Force ◽  
Cross Flow ◽  
Open Loop ◽  
Diameter Ratio ◽  
Force Level ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
System Integrity ◽  
Tube Bundles

The integrity of tube bundles is very important especially when dealing with high-risk applications such as nuclear steam generators. A major issue to system integrity is the flow-induced vibration (FIV). FIV is manifested through several mechanisms including the most severe mechanism; fluidelastic instability (FEI). Tube vibration can be constrained by using tube supports. However, clearances between the tube and their support are required to allow for thermal expansion and for other manufacturing considerations. The clearance between tubes may allow frequent impact and friction between tube and support. This in turn may cause fatigue and wear at support and potential for catastrophic tube failure. This study aims to investigate the dynamics of loosely supported tube array subjected to cross-flow. The work is performed experimentally in an open-loop wind tunnel to address this issue. A loosely-supported single flexible tube in both triangle and square arrays subjected to cross-flow with a pitch-to-diameter ratio of 1.5 and 1.733, respectively were considered. The effect of the flow approach angle, as well as the support clearance on the tube response, are investigated. In addition, the parameters that affect tube wear such as impact force level are presented.

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.

Wear Transitions of Tube-Support Components for a Nuclear Steam Generator under Fretting Conditions

2006 ◽  
Vol 326-328 ◽  
pp. 1263-1266 ◽  
Author(s):  
Sung Hoon Jeong ◽  
Jung Min Park ◽  
Joong Hui Lee ◽  
Young Ze Lee
Keyword(s):  
Nuclear Power ◽  
Applied Load ◽  
Fluid Flows ◽  
Relative Displacement ◽  
Fretting Wear ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
Support Materials ◽  
Mild Wear ◽  
Inconel 690

Tubes in nuclear steam generators are held up by supports because the tubes are long and slender. Fluid flows of high-pressure and high-temperature in the tubes cause oscillating motions between tubes and supports. This is called as FIV (flow induced vibration), which causes fretting wear in contact parts of tube-support. The fretting wear of tube-support can threaten the safety of nuclear power plant. Therefore, a research about the fretting wear characteristics of tube-support is required. This work is focused on fretting wear transitions from mild wear to severe wear of tube-support materials by various loads and relative displacements. The transition is defined on the basis of the changes in wear amount. To investigate the transition, the fretting wear tester was contrived to prevent the reduction of relative displacement between tube and support by increasing the load. The tube and support materials were Inconel 690 and 409 SS, respectively. The results show that the transition of tube-support wear is caused by the changes of the dominant wear mechanism depending on the applied load and the relative displacement.

Experimental Fretting-Wear Studies of Steam Generator Materials

1995 ◽  
Vol 117 (4) ◽  
pp. 312-320 ◽  
Author(s):  
N. J. Fisher ◽  
A. B. Chow ◽  
M. K. Weckwerth
Keyword(s):  
Steam Generator ◽  
Contact Force ◽  
Environmental Conditions ◽  
Analytical Techniques ◽  
Work Rate ◽  
Fretting Wear ◽  
Flow Induced Vibration ◽  
Dynamic Interactions ◽  
Support Materials ◽  
Wear Damage

Flow-induced vibration of steam generator tubes results in fretting-wear damage due to impacting and rubbing of the tubes against their supports. This damage can be predicted by computing tube response to flow-induced excitation forces using analytical techniques, and then relating this response to resultant wear damage using experimentally derived wear coefficients. Fretting-wear of steam generator materials has been studied experimentally at Chalk River Laboratories for two decades. Tests are conducted in machines that simulate steam generator environmental conditions and tube-to-support dynamic interactions. Different tube and support materials, tube-to-support clearances, and tube support geometries have been studied. The effect of environmental conditions, such as temperature, oxygen content, pH and chemistry control additive, have been investigated as well. Early studies showed that damage was related to contact force as long as other parameters, such as geometry and motion, were held constant. Later studies have shown that damage is related to a parameter called work-rate, which combines both contact force and sliding distance. Results of short and long-term fretting-wear tests for CANDU steam generator materials at realistic environmental conditions are presented. These results demonstrate that work-rate is an appropriate correlating parameter for impact-sliding interaction.

Vibration Analysis of Steam Generators and Heat Exchangers: An Overview — Part II: Vibration, Response, Fretting-Wear, Guidelines

2002 ◽  
Author(s):  
Michel J. Pettigrew ◽  
Colette E. Taylor
Keyword(s):  
Heat Exchangers ◽  
Vibration Analysis ◽  
Response Prediction ◽  
Design Guidelines ◽  
Vibration Response ◽  
Fretting Wear ◽  
Steam Generators ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Service Water

Design guidelines were developed to prevent tube failures due to excessive flow-induced vibration in shell-and-tube heat exchangers. An overview of vibration analysis procedures and recommended design guidelines is presented in this paper. This paper pertains to liquid, gas and two-phase heat exchangers such as nuclear steam generators, reboilers, coolers, service water heat exchangers, condensers, and moisture-separator-reheaters. Part 2 of this paper covers forced vibration excitation mechanisms, vibration response prediction, resulting damage assessment, and acceptance criteria.

Study on the Vibrational Characteristics of a Tube Array Caused by Two-Phase Flow—Part 1: Random Vibration

1992 ◽  
Vol 114 (4) ◽  
pp. 472-478 ◽  
Author(s):  
T. Nakamura ◽  
K. Fujita ◽  
K. Kawanishi ◽  
N. Yamaguchi ◽  
A. Tsuge
Keyword(s):  
Random Vibration ◽  
Two Phase Flow ◽  
Impact Force ◽  
Phase Flow ◽  
Liquid Slug ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Vibrational Characteristics ◽  
Flow Part ◽  
The Impact

There are few published papers about the flow-induced vibration caused by two-phase flow. Especially, the experimental data at high-pressure and high-temperature conditions which corresponds to the practical phenomenon, are extremely few, and the mechanism of the two-phase flow-induced load acting on a tube in tube array has not yet been explained. This paper shows the experimental results about the turbulent buffeting force both by air-water two-phase flow and by steam-water flow of extreme conditions up to 5.8 MPa in pressure and 272°C in temperature, the explanation of the mechanism of this force, and the method to evaluate the response of the tube caused by two-phase flow. Here, the main source of the buffeting force by two-phase flow in slug or froth flow pattern is recognized to be the impact force caused by the intermittently rising liquid slug. The slug speed and the fluid force acting on a tube are estimated, combined with the estimation of the intermittence of the occurrence of the liquid slug rising.

Analytical and Experimental Flow-Induced Vibration Analysis of a Shell and Tube Cooling Water Heat Exchanger

2002 ◽  
Author(s):  
Alberto F. Marti´n Ghiselli ◽  
Rau´l M. Kulichevsky ◽  
Mauricio A. Sacchi ◽  
Alberto J. Pastorini ◽  
Ce´sar G. Belinco
Keyword(s):  
Heat Exchanger ◽  
Cooling Water ◽  
Fretting Wear ◽  
Design Stage ◽  
Dynamical Response ◽  
Original Design ◽  
Flow Induced Vibration ◽  
Design Modification ◽  
Operational Conditions ◽  
Shell And Tube

A flow-induced vibration problem evaluation of a shell and tube cooling water heat exchanger equipment installed in a power plant is presented in this paper. The problem produced loss of thickness in many tubes of the bundle, by impact or fretting wear, and the need to plug these tubes to avoid leakage. These vibrations could had been produced by changes in the equipment operational conditions or by a wrong evaluation during the design stage. An analytical and experimental evaluation was made to predict tubes dynamical response and to identify the excitation mechanisms. The original design modification adopted to solve the problem is presented and evaluated.

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