Deformation Characteristics of Pipe Flanges Due to Bolt Loads and Internal Pressure

Deformation characteristics of pipe flanges are important in the leak rate based design of gasketed flanged connections. Not only the equilibrium of force between bolts and the clamped parts including flanges and a gasket but also the displacement between them should be considered in the design of gasketed flanged connections. Recently, finite element method (FEM) has widely been used in the analysis of flanged connections. However, analyses of pipe flanges based on the analytical method using classical theories such as the strength of materials are still important when parametric calculations of flanges are necessary. In this study, a method to analyze the stress and deformation of welding neck type flanges is demonstrated and the validity of the analysis is checked by experiment. A software using Visual Basic for Applications (VBA) is developed based on the method. The advantages of the software are that stresses and deformation of flanges are easily calculated by selecting a flange size and design conditions from a database. The validity of the results obtained by the software is also confirmed by comparing the calculated results with those obtained by FEA. A series of calculations have been done for Japanese Industrial Standard (JIS) flanges and the deformation characteristics are clarified when a flange is subjected to bolt loads and an internal pressure.