Piping Vibration and Vibration Damage Prevention Through Screening of Dynamic Susceptibility

This paper continues our recent discussion on piping vibration and practical measures for preventing vibration-related damage in nuclear power industries. Our emphasis is on an empirical approach, which attempts to estimate a so-called “dynamic susceptibility” at various locations in a piping system. This approach uses a dynamic susceptibility factor (DS), which is a quotient of the modal stress to the modal velocity, as an indicator of the risk levels of vibration to measure the vibration sensitivity for excitation sources in a given frequency interval of particular interest. In the present paper, Benchmark examples tested by the general purpose finite element program ANSYS, and commercial piping programs CAEPIPE and PIPESTRESS, are presented and the potential of using DS parameters as a screening tool for determining “potentially-large” alternating stresses is illustrated. It is demonstrated that, combined with knowledge of typical vibration sources, this is a practical and cost effective way for forming a base for the vibration control prior to installation and for the planning of post-installation vibration monitoring of a piping system under operation.