Hi,

For high pressure pulsation lines from reciprocating pump as per API 675. We need to do Acoustic and Mechanical response analysis.

After getting acoustic analysis (Approach 2)report done by third party, whether Mechanical response analysis can be done with Caesar II software ?

As we know the peak to peak pressure pulsation value and the force at every change in direction.

We can model (input) these forces at every change in direction (elbow) of piping system. and see the stress in the pipe for these forces. Check these stresses against fatigue allowable.

For Mechanical frequency of piping, we can run Model analysis in Caesar II, and will get the natural frequency of piping system.

Thus is it necessary to do Mechanical response analysis using software like BETA, PULSIM. etc?

What is lacking if we do Model analysis & static equivalent of shaking force in Caesar II analysis ?

Your prompt reply on above topic will be appreciated.

Regards,
Sunil Katwe

Hi Sunil,

After the pressure pulsations are within API allowables for all frequencies for both the suction and discharge piping sides of the pump, the mechanical pulsation study should be conducted. There are typically two steps to the mechanical analysis:

Step 1: Mechanical and Acoustic Frequency Separation
Step 2: Harmonic Mechanical Analysis at Discrete Fourier Frequencies.

The second step of the mechanical response analysis applies the shaking forces from the discrete Fourier acoustical analysis to the mechanical piping system. The calculated pipe stresses are compared to the fatigue curves for the applicable materials.