Study of mechanical aspects of leak tightness in a pressure relief valve using advanced FE-analysis
Journal of Loss Prevention in the Process Industries
2016) Study of mechanical aspects of leak tightness in a pressure relief valve using advanced FE-analysis. Journal of Loss Prevention in the Process Industries, 43. pp. 61-74. ISSN 0950-4230 , http://dx. Abstract This paper presents a numerical study involving the deformation of contact faces in the metal-to-metal seal in a typical pressure relief valve. The valve geometry is simplified to an axisymmetric problem, which comprises a simple geometry consisting of only 3 components. A cylindrical
... ozzle, which has a valve seat on top, contacts with a disk, which is preloaded by a compressed linear spring. All the components are made of AISI type 316N(L) steel defined using the multilinear kinematic hardening model based on monotonic and cyclic tests at 20 • C. In-service observations show that there is a limited fluid leakage through the valve seat at operational pressures about 90% of the set pressure, which is caused by the fluid penetrating into surface asperities at the microscale. Nonlinear FEA in ANSYS using the fluid pressure penetration (FPP) technique revealed that there is a limited amount of fluid penetrating into gap, which is caused by the plastic deformation of the valve seat at the macroscale. Prediction of the fluid pressure distribution over the valve seat just before the valve lift is addressed in this study considering the FPP interaction on multiscale. This is the principal scope, since it allows adjustment of the valve spring force in order to improve the leak tightness. Song et al. (2013) observed that in actual usage PRVs can sometimes start to release fluid prior to their set pressures P set . This is particularly true when P set is defined as the opening pressure and can result in a degradation of leak tightness for operation pressure P op , which is typically 90% of P set . This 50 study models the structure of the valve seat-disc interface in order to look at the fluid pressure penetration effects. Advanced FEA is used to investigate and quantify the influence of these effects on a spring force, which is required to provide a reliable leak tightness for pressures below P set .