Characteristics and evaluation method of flow-induced vibration at tee connection caused by high velocity

In the process plant, random vibration excited by the turbulence generated at tee connection might cause problem such as piping damage. In general, the beam mode piping vibration is known to be excited when the internal flow of the piping is the severe turbulent conditions. However, the shell mode piping vibration could occur when the piping stiffness of the circumferential direction is relatively low. In this study, an experiment was executed in order to obtain the basic characteristics of flow induced vibration at tee connection downstream. The experiment results showed the dominated vibration is circumferential direction and the dominated vibration source is the turbulence generated at tee connection. In order to evaluate the integrity of the piping system for the tee connection downstream against flow induced vibration, a new evaluation index is investigated based on the experimental results and random vibration theory. As a result, it was confirmed that the new evaluation index tends to be proportional to the shell mode stress of the random vibration.