Vibration Analysis on Piping Systems

Summary

Vibration of piping systems may be induced by internal pipe flow behavior such as pulsation, two phase and turbulence or external pipe flow such as wind. Such piping vibration is generally termed “Flow Induced Vibration (FIV)” and has a potential to cause damage of the piping systems. It is therefore important to reflect the expected FIV characteristics into design of the piping system including pipe supports. For this purpose, piping vibration analysis is indispensable technology to ensure design soundness or to investigate counter-measures against FIV.

Application Example of Piping Vibration Analysis

Severe resonant vibration was expected by pulsation analysis at piping system connecting to reciprocating compressors (Fig.1). The dominant excitation frequencies due to pulsation were expected to be less than 22Hz. However, the lowest piping mechanical natural frequency in original support design was 8Hz although this frequency should be fully higher than the excitation frequency threshold of 22Hz. It was judged necessary to provide additional pipe supports and to make some support type change in order to prevent resonance between piping mechanical natural frequencies and dominant pulsation frequencies. In the piping system reflecting such design improvement (Fig.2), no severe vibration was observed during plant’s commercial operation.
TOYO utilizes such vibration analysis to ensure flawless engineering executions and swift field trouble shootings.

(a) Original Piping Configuration

(a) Original Piping Configuration

(b) Mechanical Vibration Mode at the Lowest Natural Frequency (8Hz) Fig.1 Original Piping Design

(b) Mechanical Vibration Mode at the Lowest Natural Frequency (8Hz)
Fig.1 Original Piping Design

(a) Improved Piping Configuration

(a) Improved Piping Configuration

(b) Mechanical Vibration Mode at the Lowest Natural Frequency (27Hz) Fig.2 Improved Piping Design

(b) Mechanical Vibration Mode at the Lowest Natural Frequency (27Hz)
Fig.2 Improved Piping Design