The Experts below are selected from a list of 21 Experts worldwide ranked by ideXlab platform
G D T Carmichael - One of the best experts on this subject based on the ideXlab platform.
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An assessment of primary system stresses on the creep behaviour of high temperature Steam Piping Systems
2016Co-Authors: G D T CarmichaelAbstract:The effects of creep on the primary system loadings sustained by high temperature Steam Piping layouts are ignored in design. A detailed evaluation of the consequences of this omission is presented from both the theoretical and practical viewpoints. Piping analyses show that $Systems are not supported correctly this can give rise to enhanced primary stresses. In these circumstances if the creep strength of any part of weldments is signgcantly less than the average rupture strength of the parent material circum-ferential cracking may occur in the design lifetime. A feature of the results obtained from creep analyses is that over-stressed Systems tend to sink with time. I t is proposed that this characteristic can be used to help decide which Piping Systems should have their welds examined. NOTATION basic characteristic of a Drimarv stress is that it is no
Jiayi Wu - One of the best experts on this subject based on the ideXlab platform.
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aerodynamics analysis of superheated Steam flow through multi stage perforated plates
International Journal of Heat and Mass Transfer, 2019Co-Authors: Jiayi WuAbstract:Abstract Superheated Steam is the main medium in the Piping system of Steam power plants. In these pipelines, perforated plates are widely used to regulate the flow rate, pressure, and also reduce aerodynamics noise of Steam. For the superheated Steam flow, the flow resistance and aerodynamic noise are two key parameters of the perforated plates. In order to investigate the flow resistance and Steam aerodynamic characteristics, this paper presents a systematic study of superheated Steam and water through multi-stage perforated plates under a wide range of operating conditions with both experimental and numerical methods. The experiments are conducted out to validate the applicability of the adopted numerical models. Then numerical methods are used to investigate the water flow resistance and the Mach number distributions of the Steam flow with different structural parameters. The results show that with the increase of the holes diameter, the pressure drop decreases and the Mach number increases. Mach number drops significantly when the position of side holes moves towards the edge of the perforated plate. A critical stage distance is found, at which the pressure drop has the maximum value. Besides, the occurrence probability of supersonic Steam flow increases as the decrease of stage distance under a restricted space, and the disturbed length of supersonic Steam flow is longer when the stage distance is smaller. This work can be referred by someone who deals with perforated plate design in Steam Piping Systems or related research topics.
Rayne Gle - One of the best experts on this subject based on the ideXlab platform.
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Creep of welded branched pipes
2004Co-Authors: Rayne GleAbstract:Creep failure of welds in high-temperature power plant Steam Piping Systems is known to be a potential cause of plant failure. Creep behaviour of plain pipes with circumferential welds and cross-weld specimens have received fairly extensive attention. However, research into the creep behaviour of welded thick-walled branched Steam pipes has received less attention. Consequently, this thesis addresses improving the understanding of the creep behaviour for this type of geometry. Numerical and analytical methods are used to assess the creep behaviour of typical power plant branched pipe geometries. The effects of various geometric and material parameters on the creep stress and creep life behaviour of the connections are studied. In particular, the effect of the differing creep properties associated with the various material regions of the weld are investigated. The importance of incorporation of weld properties in creep life assessments is thus assessed. Finite element steady-state and continuum damage mechanics creep analyses have been used to identify the relative creep strength of typical connections compared to plain pipes. The work identifies typical creep rupture locations within branched pipe welds and the associated damage accumulation at and around these positions. Various creep life assessment methods/procedures are used in practise: these are mainly the British Standard codes, British Energy's R5 procedure, steady state creep approaches and continuum damage mechanics approaches. The relative accuracy and conservatism of these distinct approaches are addressed for the application to typical branched pipes. The general formulation of steady-state creep stress is applied to the parametric study of weld materials in a typical multi-material welded branched pipe. An approximate interpolation technique for power-law creep is implemented to reduce the number of analyses needed to span a wide range of material parameters. The method is used to estimate the creep stresses and lives at several critical regions within the various material zones of the weld. The advantages of the technique are related to the small number of analyses required and the simple and compact way of presenting the results for weld design and life assessment purposes.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
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Creep of welded branched pipes
1Co-Authors: Rayne GleAbstract:Creep failure of welds in high-temperature power plant Steam Piping Systems is known to be a potential cause of plant failure. Creep behaviour of plain pipes with circumferential welds and cross-weld specimens have received fairly extensive attention. However, research into the creep behaviour of welded thick-walled branched Steam pipes has received less attention. Consequently, this thesis addresses improving the understanding of the creep behaviour for this type of geometry. Numerical and analytical methods are used to assess the creep behaviour of typical power plant branched pipe geometries. The effects of various geometric and material parameters on the creep stress and creep life behaviour of the connections are studied. In particular, the effect of the differing creep properties associated with the various material regions of the weld are investigated. The importance of incorporation of weld properties in creep life assessments is thus assessed. Finite element steady-state and continuum damage mechanics creep analyses have been used to identify the relative creep strength of typical connections compared to plain pipes. The work identifies typical creep rupture locations within branched pipe welds and the associated damage accumulation at and around these positions. Various creep life assessment methods/procedures are used in practise: these are mainly the British Standard codes, British Energy's R5 procedure, steady state creep approaches and continuum damage mechanics approaches. The relative accuracy and conservatism of these distinct approaches are addressed for the application to typical branched pipes. The general formulation of steady-state creep stress is applied to the parametric study of weld materials in a typical multi-material welded branched pipe. An approximate interpolation technique for power-law creep is implemented to reduce the number of analyses needed to span a wide range of material parameters. The method is used to estimate the creep stresses and lives at several critical regions within the various material zones of the weld. The advantages of the technique are related to the small number of analyses required and the simple and compact way of presenting the results for weld design and life assessment purposes
Fabio Camilo Hipolito - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Methodologies for analysis of Steam Piping Systems subjected to Steam Hammer loadings
Universidade de São Paulo, 2016Co-Authors: Fabio Camilo HipolitoAbstract:Carregamentos transientes termo hidráulicos do tipo Steam Hammer são eventos comuns em sistemas de tubulações de vapor com grandes potenciais de catástrofes em plantas de geração de energia. Uma vez iniciado o evento, ondas de pressões são geradas com amplitudes, geralmente, de grande magnitude ocasionando altas pressões no sistema, ruídos, deformações, fadiga, com possibilidade de danos materiais e econômicos e em casos extremos fatalidades. Os procedimentos da indústria para análise deste tipo de sistema consistem realização de análises estáticas equivalentes ou análise de espectro de resposta com carregamentos caracterizados por meio de métodos analíticos baseados em hipóteses simplificadoras do fluido e fluxo. Neste trabalho é proposta a analise de sistema de tubulações por meio do método de integração numérica com superposição modal e carregamento caracterizado por método numérico com base no método das características. Comparações foram efetuadas entre os resultados obtidos pela metodologia proposta e os procedimentos da indústria, demonstrando que, dado ao alto grau de conservadorismo, os procedimentos da indústria acarretam em superdimensionamento de estruturas e tubulações ocasionando custos adicionais de projeto, sendo a otimização do projeto obtida aplicando-se a metodologia proposta no trabalho.Steam Hammer is a common transient thermo hydraulic event in Steam Piping Systems with potential to cause serious damages in power generation plants. It generates pressure waves, generally of great amplitude and magnitude, causing high pressures in the system, associated with noise, with possible material and economic damages and, in extreme case, even fatalities. Industry procedures for analysis of these events consists of performing equivalent static analysis, or response spectrum analysis, with transient loadings calculated by analytical methods based on assumptions of fluid and flow. This paper proposes a new methodology for the Piping system analysis by the numerical integration method with modal superposition and transient loadings calculated by a numerical method based on the method of characteristics. Comparisons were made between the results obtained by the proposed methodology and the stablished industry procedures, confirming that, due to the high degree of conservatism, industry procedures can lead to additional cost to the design, with the optimization of the design being obtained by applying the methodology proposed in this paper
T B Mccall - One of the best experts on this subject based on the ideXlab platform.
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safety considerations for condensation induced water hammer in Steam Piping Systems
Transactions of the American Nuclear Society, 1994Co-Authors: D Squarer, R M Roidt, T B MccallAbstract:The phenomenon of condensation induced water hammer may occur when subcooled water and Steam interact and form a water slug by rapid Steam condensation, and the slug is accelerated through the Piping by the full system pressure. The sudden deceleration of the slug by existing liquid in the system, or by any part of the Piping system can produce large pressure pulses, that by themselves or in combination with other loads, can rupture the Piping system. This paper describes the results of a study on condensation induced water hammer in a specific Piping geometry, and lists recommendations that when implemented will prevent Piping system failure.