If i have measured vibration data or calculated data as below,
is it possible to estimate allowable fatigue life time of piping?

1. Vibration frequency :12 Hz
2. Measured Velocity : 10 mm/s rms
3. Dynamic stress values are not measured .
but calculated : 25 mpa.

Assume that this measured point is the middle of straight run pipe.

CAESAR would have you calculate a displacement and apply it in the positive and then negative directions. Subtract the two states from each other as a fatigue case, and then CAESAR will estimate loss of life in one cycle. However, if you're already experiencing 12 Hz without failure for any reasonable period of time (this is 1MM cycles per day), CAESAR may likely state you're effectively are 0 loss of life or it's already failed.

However, I invite you to look at the fatigue curves already within CAESAR to get an idea of what you're looking for. On the "allowable stresses" tab, there's a "Fatigue Curves..." button with Intergraph-supplied fatigue curves.