Dear All ,

I am doing harmonic analysis of a piping system which is connected between Heater & column .The piping is subjected to low frequency vibrations which are harmonic in nature . This is most probably due to mechanical resonance .The vibration zone is away from the both equipments .

I need Field vibration data in the form which is most suitable to do harmonic analysis in Caesar II . so that I can input excitation frequency & harmonic displacement . In my case , I have to give instruction to site person for vibration measurement .

In my opinion , the vibration measurement will be done in the form of vibration Displacement & frequency . First the site person has to find out the locations at which vibration amplitude(displacement ) is high or moderate . Then he has to find out the frequency corresponding to each location , so that a frequency range can be find out at which vibration is occurring at the site .Then a frequency need to be found out at which maximum no. of peak is observed on the vibration analyser. Then the probe of the analyser to be set at that frequency at which maximum peaks is observed at vibrating location in the piping system and the Displacement readings to be recorded.

By this we will get the target excitation (forcing) frequency & harmonic displacement to start the harmonic fatigue analysis in the Caesar II .

I need valuable suggestions regarding the above mentioned procedure for field vibration measurement .

Regards ,

Don't simply pick harmonic displacement at some random point as your applied load. Provide data that describes the true applied load. If you think it's mechanical vibration, it's probably an equipment connection. Acoustic vibration and pulsation would be (properly) applied forces.

Dave , Thanks for your response!

In my case the vibration zone is very far away from the equipments.
I agree that vibration at some random point may not represent the applied force.

The location where vibration(displacement) is maximum may represent the applied load .The same has been written in previous statement.Please tell , can i use the above mentioned procedure for vibration measurement at site .

In case it is not the correct way then Please advice me how should i instruct site person so that he can take vibration reading in most useful form which is required for harmonic analysis in Caesar II for fatigue life evaluation of the piping system .

The vibration measurement company can also measure the stress levels in the affected zone. If the measured stress levels are beyond the fatigue limit, additional supporting measure can be found out or dampners can be added in affected zone to resuce vibrations.