Effect of Twin Gasket and Internal Fluid on the Dynamic Behavior of Pipeline with Flange Joint

Piping system with flange joints used in the field is subjected to dynamic loads, due to both external and internal excitations. In the present study, the dynamic behavior of the system is studied with finite element analysis using the perturbation technique and validated with the roving hammer experiment. The analysis is focused on the influence of fluid and pre-stress caused due to static loads, on the dynamic behavior of the system. The nonlinearities due to joint and material behavior are included by using the perturbation technique, to account for the complex behavior. The system having a flange joint with twin gasket (two concentric gaskets having half-width of single gasket) provides better performance under static loads. Its effect on dynamic loads and the failure modes due to structural integrity and leakage is studied. Results show that twin gasket can withstand a higher safe harmonic load compared to the single gasket, based on stress variation in gasket even though the gasket configuration is insignificant in the modal behavior, i.e., natural frequencies and mode shapes. Upon including the fluid, the natural frequencies of the system decrease with a marginal increase in damping factor.