Remaining Life Evaluation Based on Strain Deformation Monitoring
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TECHNICAL ARTICLE—PEER-REVIEWED
Remaining Life Evaluation Based on Strain Deformation Monitoring Fernanda Figueiredo Martins dos Santos . Heloisa Cunha Furtado . Luiz Henrique de Almeida
Submitted: 30 January 2018 / in revised form: 12 April 2018 ASM International 2018
Abstract The operating conditions of a power plant affect its structural integrity due to many degradation mechanisms, among which is creep. Strain measurements constitute a relatively simple and reliable method of obtaining accurate data regarding the capability of engineering materials to withstand loads and of determining stress distribution in all manner of structural components. This work carried out a critical evaluation of the application of a high-temperature strain gage on a strain and stress analysis. The sensor was undergoing a group of long-term creep tests whose results were compared with the creep machine’s acquisition system. The same strain gage was part of a monitoring system and its out some used on the remaining life evaluation a power plant’s pipeline. The methodology consists of online strain monitoring of those components or regions more susceptible to creep failure, which were identified by finite element analysis. The long-term creep tests using high-temperature strain gages showed that the relative position between sensor and the sample necking region exercises great influence on the measured results. Linear relationship between minimum creep rate obtained by strain gages and rupture time values was observed. The power plant pipeline analysis showed that thermomechanical fatigue is the predominant degradation mechanism. F. F. M. dos Santos (&) H. C. Furtado CEPEL - Centro de Pesquisas de Energia Eletrica, Rio de Janeiro, Brazil e-mail: [email protected]; [email protected] H. C. Furtado e-mail: [email protected] L. H. de Almeida COPPE - Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil e-mail: [email protected]
Keywords Remaining life Power plant Strain monitoring
Introduction Thermal power plants and refineries are aging around the world and their components and pipes have their life limited by prolonged exposure to high-temperature, highpressure and aggressive environments. Furthermore, the industrial progress of countries requires not only the development of novel energy resources, but also an increase in the efficiency of current power generation, such as fire ones. Improvements in efficiency result essentially from increasing in the steam pressure and temperature, leading to higher thermal and mechanical loading of the piping components [1, 2]. The operating conditions of a power plant affect its structural integrity affected by many degradation mechanisms, among which is creep. The assessment of creep damage and its correlation with the components remaining life is essential to ensure a continued safe operation of the plant. These analyses have been recognized by the industry as extremely important since the assurance of safe operation, reduction of unnecessary shutdowns for inspection and
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