Pipe natural frequency of 4 Hz.

[amateurpipe]

I have come across many projects where a piping system carrying two phase fluid is to be designed to have a natural frequency of 4 Hz or more.
My question is from where do we arrive at the figure of 4 Hz ? How does a natural frequency of piping system more than this figure ensure that the pipe is safe from vibrations ?

 

[SNORGY]

I believe 4 Hz is where the piping is most susceptible to unacceptable vibration excitation due to wind.

thread378-49424


Regards,

SNORGY.

 

[C2it]

It's a commonly used go-by and really nothing more. A Norsok standard recommended it (mostly related to offshore installations) to limit risk of vortex induced excitation.

Such a value could not be used with larger bore refinery pipework without excessive restraint.