Study on the Sealing Performance of Pipe Flange Connections at Elevated Temperature by Computational Mechanics

1. 考虑接触热阻的温度分析数值计算方法将接触热阻的经验方程引入到可处理热行为和结构分析的商业程序中，建立了高精度的三维温度分析数值计算方法。2 .利用上述方法，较全面地阐明了供体在螺栓接头周围的流动规律和螺栓轴向力大小的变化规律。利用精确几何形状的管道法兰模型，分析了管道法兰的温度场和应力场，并对管道法兰热变形引起的轴向螺栓力的变化进行了评价。研制了一种可产生高达30mpa的压缩压力，可使垫片温度升高300度的压缩试验设备。得到了从室温到150℃的不同温度下片状垫片的压缩曲线。高温下垫片材料性能对密封性能的影响利用得到的压缩曲线，研究了高温下垫片刚度变化对密封性能的影响。为了建立管道法兰连接在高温下的拧紧操作准则，建立了一个数值计算程序，为分析管道法兰连接的热力学行为提供了刚性基础

1. Numerical Procedure for Temperature Analysis by Taking Account of Thermal Contact resistance A three-dimensional numerical procedure with high accuracy for temperature analysis has been established by incorporating the empirical equation for thermal contact resistance into a commercial program which can deal with thermal behavior and structural analysis.2. Elucidations of the Heat Flow Pattern around Bolted Joint and the Mechanism of Bolt Preload Variation It has been comprehensively elucidated using the above method how the supplied heal flows around the bolted joint and the magnitude of axial bolt force varies.3. Temperature and Stress Analysis of Pipe Flange Connections subjected to Thermal Load Using pipe flange models with accurate geometry, its temperature and stress fields were analyzed, and the variations of axial bolt force due to the thermal deformation of pipe flange have been evaluated.4. Development of Compression Test Equipment for Sheet Gaskets at Elevated Temperature A compression test equipment which can generate the compressive pressure up to30MPa and increase the gasket temperature as high as 300 deg. has been developed. Compression curves of sheet gaskets were obtained at various temperatures from room temperature to 150 deg.5. Effects of Material Properties of Gaskets at Elevated Temperature on the Sealing Performance Using the compression curves so obtained, it has been investigated how the stiffness variation of gaskets at elevated temperature affects the tightening characteristics.6. Guideline for the Tightening Operation of Pipe Flange Connections at Elevated Temperature In order to establish a guideline for the tightening operation of pipe flange connections at elevated temperature, a numerical procedure, which provides a rigid foundation to analyze thermal and mechanical behaviors of pipe flange connections, has been established