Fatigue Life Estimation of Piping System for Evaluation of Acoustically Induced Vibration (AIV)

One of the key design parameters to a process plant with large capacity is the risk of AIV (Acoustically Induced Vibration) on the flare piping system. AIV is a piping vibration phenomenon exhibiting high frequencies caused by large acoustic power generated by the pressure drop across a PRV (Pressure Relief Valve). The evaluation method for susceptibility of piping to AIV fatigue failure was first proposed by Carucci and Mueller around 30 years ago. Since then, several developments were reported. However, there has not been publication with reference to fatigue life estimation in relation to the AIV phenomena. This paper proposes a procedure to calculate the fatigue life for the AIV based on actual operating condition, design fatigue life curve, etc. In this procedure vibration stress level can be obtained from the expected sound power level. The stress level was then used to estimate the fatigue life using design fatigue life curve and AIV experimental data. It is hoped that this procedure would allow for possible AIV failures to be classified corresponding to the actual plant operation. This kind of AIV evaluation would be useful to determine the priority of the countermeasure to mitigate piping failure caused by AIV in the existing plant.