Application of Hot Hardness Test to the Evaluation of Creep Damage in Cr-Mo-V Turbine Rotor of Fossil Power Plant

2004 ◽  
Author(s):  
Shinsuke Sakai ◽  
Satoshi Izumi ◽  
Takashi Murakami ◽  
Akito Nitta ◽  
Junichi Kusumoto ◽  
...  
Keyword(s):  
Power Plants ◽  
Residual Life ◽  
Creep Damage ◽  
Hardness Test ◽  
Turbine Rotor ◽  
Constitutive Law ◽  
Life Evaluation ◽  
Site Evaluation ◽  
Fossil Power Plant ◽  
Hot Hardness

In residual life evaluation of fossil power plants, improvement of accuracy of creep damage evaluation is extremely important. One of the powerful non-destructive evaluation methods is hardness test. This method is effective because it enables us the on-site evaluation and the results are obtained without laborious work. However, in order to make it more powerful method, improvement of accuracy is inevitable. In this paper, the Vickers hardness test not at ambient but at high temperature is applied to the deteriorated rotor material and the method for the residual life evaluation with high accuracy is newly developed. In the method, creep constitutive law is determined from the results of hot hardness test first. Next, the variation of constitutive law with the creep damage is investigated. Finally, the dependency of exponent of constitutive law on the creep damage is shown and the method to evaluate the creep damage from this dependency will be proposed.

Codes and Standards for Managing Degradation of Boilers in Service

2020 ◽  
Author(s):  
Corrado Delle Site ◽  
Emanuele Artenio ◽  
Gennaro Sepede ◽  
Matteo Chini ◽  
Francesco Giacobbe
Keyword(s):  
Service Time ◽  
Power Plants ◽  
Residual Life ◽  
Creep Damage ◽  
Pressure Vessels ◽  
Steam Boilers ◽  
Critical Components ◽  
Set Up ◽  
Effective Use ◽  
Life Consumption

Abstract Degradation of pressure equipment is becoming an important issue due to increasing asset service time in process and power plants across Europe. For this reason it is important to assess life consumption of these assets to avoid catastrophic failures. Therefore it is necessary to refer to national/international normative on this subject. At present time the Italian thermotechnical committee (CTI) has drawn up a comprehensive set of norms which help the user to set up an inspection plan to investigate and assess degradation of pressure vessels and boilers. In the first part of this paper creep damage of Steam Generators is analyzed. For this purpose results of INAIL (Istituto Nazionale per l’ Assicurazione contro gli Infortuni sul Lavoro) database of steam boilers with 100’000 service hours or more is illustrated. Critical components are identified with reference to materials, geometry and operating parameters (pressure, temperature and time). At the end of the design life cycle, components of pressure equipment operated in creep regime must subjected to specific checks to estimate their residual life and the suitability for further use in safety conditions. The procedure allows to define reinspection intervals keeping acceptable the risk associated with the further use of the component related to creep even in evidence of defects in progress. The first check must be performed after 100,000 hours of effective use. Then, residual life evaluations must be repeated according to period of time that are defined as function of the results of all the checks carried out. In the second part of this paper boiler degradation is discussed with reference to NDT results and in-field inspection campaigns which are carried out traditionally after 45 years of service time, to minimize the risk of pressure components failures. In this paper results of different case studies are discussed with reference to degradation mechanisms and applicable standards.

Development of Compact Small Punch Creep Testing Equipment

2011 ◽  
Author(s):  
Hajime Watanabe ◽  
Akihiro Kanaya ◽  
Junichi Kusumoto ◽  
Takafumi Tsurui
Keyword(s):  
Power Plant ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Residual Life ◽  
Thermal Power ◽  
Creep Property ◽  
Testing Equipment ◽  
Creep Testing ◽  
Small Punch ◽  
Life Evaluation

Japan has many aged thermal power plant facilities and some boilers in such facilities have been in operation for more than 100,000 hours, so the importance of creep residual life evaluation of components exposed to severe conditions has been increasing. Although creep residual life of such components can be evaluated by destructive methods relatively accurately, they significantly affect the component to be sampled, take a long time to carry out and are high-cost. To solve these problems, Kobe Material Testing Laboratory Co., Ltd. and Kyushu Electric Power Co., Inc. have jointly developed compact-sized and less expensive small punch creep testing equipment for accurate creep residual life evaluation. Outer dimensions of developed equipment are 660W × 335D × 807H (mm); weight is 130kg. Small punch creep test can be conducted by this testing equipment, in order to identify creep property using 8mm diameter and 0.5mm thickness specimens taken from tubes or pipes of thermal power plant facilities, and evaluate remaining life. The testing equipment is expected to improve efficiency and reduce costs to evaluate material characteristics and creep residual life for facilities in power plants and various industries.

Effects of Primary and Secondary Creep Formulations on API 579-1 Residual Life Evaluation

2018 ◽  
Author(s):  
Lorenzo Scano ◽  
Luca Esposito
Keyword(s):  
Constitutive Equation ◽  
Residual Life ◽  
Creep Damage ◽  
Primary Creep ◽  
Secondary Creep ◽  
Time To Rupture ◽  
Life Evaluation ◽  
Omega Method ◽  
Material Constitutive Equation ◽  
Rate Formulation

A sound material constitutive equation is crucial for the residual life evaluation of pressure components operating in the creep range. In a previous work [1], the authors investigated how a secondary creep formulation encompassing both the dislocational and the diffusional range influences the assessment of damage according to API 579-1 [2] within the whole component stress range. In the present paper the work has been extended in order to include the effects of primary creep in the constitutive equation for the ASTM A335 P22 low-alloy steel used for the manufacturing of the HRSG header whose welded details were previously investigated. The creep damage was first calculated according to API 579-1 Section 10 via inelastic, time-dependent FEA and the Larson-Miller approach (LMP) with code-defined, minimum time-to-rupture data. This led to a first reckoning of the primary creep impact in terms of API 579-1 residual life for the components under evaluation. The API 579-1 time-to-rupture was then assessed with a detailed stress analysis implementing the Omega Method and its creep strain rate formulation. The obtained results were finally compared to those previously determined through the LMP procedure and the different creep correlations (secondary and primary+secondary).

On-Line Monitoring System for Main Steam Piping of Power Plants

2009 ◽  
Author(s):  
Ning Wang ◽  
Zhengdong Wang ◽  
Yingqi Chen
Keyword(s):  
Power Plant ◽  
Monitoring System ◽  
Remote Monitoring ◽  
Power Plants ◽  
Residual Life ◽  
Thermal Power ◽  
Creep Damage ◽  
Piping System ◽  
On Line ◽  
Main Steam

An on-line life prediction system is developed for remote monitoring of material aging in a main steam piping system. The stress analysis of piping system is performed by using the finite element method. A sensor network is established in the monitoring system. The creep damage is evaluated from strain gages and a relationship is given based on a database between the damage and residual life. Web technologies are used for remote monitoring to predict the residual life for every part of the piping system. This system is useful for safety assessment procedures in thermal power plant, nuclear power plant and petrochemical industries.

Effects of Secondary Creep Formulation on API 579-1 Residual Life Evaluation

2017 ◽  
Author(s):  
Lorenzo Scano ◽  
Luca Esposito
Keyword(s):  
Life Prediction ◽  
Ad Hoc ◽  
Residual Life ◽  
Creep Damage ◽  
International Standards ◽  
Secondary Creep ◽  
Creep Life ◽  
Life Evaluation ◽  
Level 3 ◽  
The Impact

Although several ad hoc procedures are codified into main international standards, the creep life prediction remains a critical phase of each Fitness-For-Service assessment. Commonly, either a time-fraction or a ductility exhaustion approach can be used. In both cases, conservative predictions within a factor of 2 or 3 are expected [1]. However, since the procedures to determine the creep damage are based upon the results of a stress analysis, the residual life evaluation can be affected by the adopted creep formulation. The choice to use a simple modeling, only accounting for the dislocational creep range, could lead to overestimate the component creep life at low stresses, and this is also subtly true even at concentration points if triaxiality or deformation-controlled loading lead to marked stress relaxation over time. In this paper, the tube to header and the header to hemispherical end joints of a HRSG assembly were assessed by the API 579-1/ASME FFS-1 [2] Level 3 procedure, via inelastic FEA, changing the creep formulation to compare the results. The classical Nortons law was replaced by more sophisticated secondary creep models to account for the complex time-dependent stress-field. In particular, the primary and secondary stress re-distribution/relaxation in the creep range were investigated in order to evaluate the impact of the steady-state creep constitutive equation on the residual life prediction.

Atomic Diffusion Induced Damage of Ni-Base Super Alloy at Elevated Temperature

2016 ◽  
Author(s):  
Motoki Takahashi ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Power Plants ◽  
Creep Damage ◽  
Rotor Blades ◽  
Atomic Scale ◽  
Atomic Diffusion ◽  
Kernel Average Misorientation ◽  
Damage Process ◽  
Creep Loading ◽  
Ebsd Method ◽  
Base Superalloy

Ni-base superalloys consisting of binary phases such as cuboidal γ’ (Ni3Al) precipitates orderly dispersed in the γ matrix (Ni-rich matrix) have been generally used for rotor blades in energy power plants. However, fine dispersed γ’ precipitates are coarsened perpendicularly to the applied load direction during high temperature creep loading. As this phenomenon called “Rafting” proceeds, the strengthened micro texture disappears and then, cracks starts to grow rapidly along the boundaries of the layered texture. Thus, it is very important to evaluate the change of the crystallinity of the alloy in detail for explicating the atomic scale damage process. In this study, the change of the micro-texture of the Ni-base superalloy (CM247LC) was observed by using EBSD method. The change in the crystallinity was evaluated using both Kernel Average Misorientation (KAM) and image quality (IQ) values. The KAM value indicates the dislocation density and the IQ value shows the order of atom arrangement in the observed area. As a result, KAM value showed no significant change with increasing the creep damage. On the other hand, the IQ value monotonically shifted to lower values and the average IQ value gradually decreased as the creep loading time increased. Decreasing IQ value without change in KAM value implies that the density of point defects such as vacancies mainly increased under creep loading and ordered Ll2 structure became disordered. Therefore, the creep damage of this alloy is mainly dominated by not the accumulation of dislocations, but the increase in the disorder of atom arrangement in the micro texture caused by the diffusion of component elements.

On real-time creep damage prediction for steam turbine

2022 ◽  
pp. 014233122110689
Author(s):  
Yongjian Sun ◽  
Bo Xu
Keyword(s):  
Finite Element ◽  
Steam Turbine ◽  
Real Time ◽  
Creep Damage ◽  
Element Model ◽  
Turbine Rotor ◽  
Theoretical Research ◽  
Element Analysis ◽  
Damage Prediction ◽  
Time Calculation

In this paper, in order to solve the calculation problem of creep damage of steam turbine rotor, a real-time calculation method based on finite element model is proposed. The temperature field and stress field of the turbine rotor are calculated using finite element analysis software. The temperature data and stress data of the crucial positions are extracted. The data of temperature, pressure, rotational speed, and stress relating to creep damage calculation are normalized. A real-time creep stress calculation model is established by multiple regression method. After that, the relation between stress and damage function is analyzed and fitted, and creep damage is calculated in real-time. A creep damage real-time calculation system is constructed for practical turbine engineering. Finally, a numerical simulation experiment is designed and carried out to verify the effectiveness of this novel approach. Contributions of present work are that a practical solution for real-time creep damage prediction of steam turbine is supplied. It relates the real-time creep damage prediction to process parameters of steam turbine, and it bridges the gap between the theoretical research works and practical engineering.

Principles of Imitation for the Loading of the Test Bench for Gas Turbines of Gas Pumping Units, Adequate to Real Conditions

2021 ◽  
Vol 13 (24) ◽  
pp. 13678
Author(s):  
Anton Petrochenkov ◽  
Aleksandr Romodin ◽  
Vladimir Kazantsev ◽  
Aleksey Sal’nikov ◽  
Sergey Bochkarev ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Simulation Models ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Automation System ◽  
Model Free ◽  
Gas Pumping ◽  
Pumping Units

The purpose of the study is to analyze the prospects for the development of loading methods for gas turbines as well as to develop a mathematical model that adequately describes the real operating conditions of the loading system at various loads and rotation speeds. A comparative analysis of the most common methods and technical means of loading the shafts of a free turbine at gas turbine plants intended for operation as part of gas pumping units is presented. Based on the results of the analysis, the expediency of using the loading model “Free Power Turbine Rotor–Hydraulic Brake” as a load simulation is shown. Recommendations for the creation of an automation system for the load testing of power plants have been developed. Mathematical models and Hardware-in-the-Loop simulation models of power plants have been developed and tested. One of the most important factors that predetermine the effectiveness of the loading principle is the possibility of software implementation of the loading means using software control systems that provide the specified loading parameters of the gas turbine.

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