Dear SErs
Modal analysis is to find natural frequency with different mode,

but how to understand this result with piping system will vibrate at site or not,

some reading says it natural frequency goes above 15hz then there is possibility of vibration, but the system give more and many natural frequency above 15hz, even the system not connected with rotating equipment it give more and many natural frequency above 15hz at site no vibration then how to predict using modal analysis to find vibration

my intension is to find out the real use of modal analysis in practical usage

some reading says the natural frequency should be kept below 6hz how to keep it below 6hz always many natural frequencies since many modes

regards
pipeman