Effect of combining angle and branch diameter for flow-induced vibration at tee connection

Abstract

In the process plant, random vibration with shell mode excited by the turbulence generated at tee connection might cause problems such as piping damage. Author proposed a new evaluation index in the previous work to evaluate the random vibration with shell mode at tee connection downstream and the adequacy of the index was confirmed by the experiment with 1.5 inch × 4 inch piping system with 45 deg combining tee connection so as to confirm the adequacy of the index proposed in the previous work. This paper presents the experimental study results to investigate the effects of branch size and combining angle. In the experiment the branch area ratio to the main pipe area were varied from 0.0146 to 1.00, and two combining angles, 90 and 45 degrees were examined. As a result, it was confirmed the proposed index could evaluate vibration stress adequately for wide range of the branch pipe area ratio. And the vibration stress for the piping system with 90 deg connection is around 1.4 times of that with 45 deg tee connection.

Keywords

• flow-induced vibration
• random vibration
• shell mode
• tee connection
• combining angle
• branch diameter