Dynamic Response Of Piping System Research Articles

Study of dynamic response of piping system with gasketed flanged joints using finite element analysis

The dynamic response of piping system with gasketed flanged joints at various temperatures is studied using finite element analysis. FE simulation with thermo-mechanical analysis is performed, followed by modal and harmonic analysis. Important parameters affecting the vibration are discussed. Temperature of internal fluid induces thermal stresses which influence the natural frequencies significantly. A comparison has been made between metal gasket and spiral wound gasket. Results show that the natural frequencies corresponding to particular modes are influenced by the type of gasket used.

Experimental Study on Seismic Responses of Piping Systems With Friction—Part 1: Large-Scale Shaking Table Vibration Test

Abstract This report deals with the experimental study of seismic response behavior of piping systems in industrial facilities such as petrochemical, oil refinery, and nuclear plants. Special attention is focused on the nonlinear dynamic response of piping systems due to frictional vibration appearing in piping and supporting devices. A three-dimensional mock-up piping and supporting structure model wherein piping is of 30-m length and 200-mm diameter is excited by a large-scale (15 m × 15 m) shaking table belonging to the National Research Institute for Earth Science and Disaster Prevention in Tsukuba, Ibaraki. Power spectra of the response vibration and the loading-response relationship in the form of a hysteresis loop under several loading conditions are obtained. The response reduction effect caused by frictional vibration is evaluated and demonstrated in terms of “response reduction factor.”

Development of Sensitivity Analysis Code for Elastic-Plastic Dynamic Response of Piping Systems

A sensitivity analysis code for the elastic-plastic dynamic response of piping systems is developed in the context of implicit time integration schemes. The formulation of sensitivity analysis originates in the perturbation method and retains its advantage. Namely, the decomposed effective stiffness matrix after the iteration for each increment is efficiently used to compute the sensitivity of any parameter involved in the piping system. A residual heat remover of a PWR (pressurized water reactor) under an earthquake loading is analyzed based on the present method with the isoparametric elbow element proposed by Bathe, and satisfactory results are obtained.

Development of Sensitivity Analysis Code for Elastic-Plastic Dynamic Response of Piping Systems.

A sensitivity analysis code for the elastic-plastic dynamic response of piping systems is developed in the context of implicit time integration schemes. The formulation of sensitivity analysis originates in the perturbation method and retain its advantage. Namely, the decomposed effective stiffness matrix after the iteration for each increment is efficiently used to compute the sensitivity of any parameter involved in the piping system. A residual heat remover of PWR under an earthquake loading is analyzed based on the present method with the isoparametric elbow element proposed by Bathe, and satisfactory results are obtained.

Response Characteristics of Piping System Supported by Visco-Elastic and Elasto-Plastic Dampers

Improving the reliability of the piping systems can be achieved by eliminating the mechanical snubber and by reducing the response of the piping. In the seismic design of piping system, damping is one of the important parameters to reduce the seismic response. It is reported that the energy dissipation at piping supports contributes to increasing the damping ratio of piping system. Visco-elastic damper (VED) and elasto-plastic damper (EPD) were developed as more reliable, high-damping piping supports. The dynamic characteristics of these dampers were studied by the component test and the full-scale piping model test. Damping effect of VED is independent of the piping response and VED can be modeled as a complex spring in the dynamic analysis. On the other hand, damping ratio of piping system supported by EPD increases with the piping response level. So, these dampers are helpful to increase the damping ratio and to reduce the dynamic response of piping system.

Dynamic response of piping system on rack structure with gaps and frictions

In the seismic design of a piping system on a rack structure, the interaction between the piping system and the rack structure must be evaluated under the condition that the rack structure is not stiff and heavy enough compared with the piping system. Moreover, there are local nonlinearities due to the gap and friction between the piping system and the rack structure. This paper presents the influence of the interaction and the local nonlinearities upon the seismic response by numerical study and a vibration test using a shaking table. In the numerical study, the piping system and the rack structure were represented by the three degrees of freedom mass-spring model taking a vibration mode of the piping system into account. The nonlinearities due to gap and friction were defined as a function of motion and treated as the pseudo force vector (additional applied force) in an equation of motion. From the results of the numerical study and the vibration test, it was clarified that seismic response of both the rack structure and the piping system is reduced by gap and friction. Moreover, the piping system and rack structure can be represented by the three degrees of freedom mass spring model. And the local nonlinearities can be treated by the pseudo force in an equation of motion.

Inelastic Response of Nuclear Piping Subjected to Rupture Forces

A numerical procedure which can be used to evaluate the inelastic dynamic response of piping systems subjected to blow-down forces is described. The following finite elements are used to represent the piping system: (1) bilinear beam element, (2) bilinear curved beam element, and (3) bilinear support element with an initial gap. The method is then used to evaluate the dynamic response of two typical segments of a main steamline.