Investigating Piping Acoustic Induced Vibration Problems and Current Assessment Methods to Evaluate Fatigue Life

Acoustic induced vibration (AIV) of piping systems is a critical problem that EPC contractors and operators must address in order to develop a safe, robust, and fit-for-service design for developing and operating their facilities (liquefaction terminals, petrochemical facilities, power plants etc.). The motivation of this paper is to expand beyond Carucci Mueller sound power level calculations in order to understand how AIV problems develop in piping systems. The paper delves deeper to identify resonant frequencies and corresponding modal stresses and how the two can be utilized to estimate the structural response. This paper discusses McDermott's approach to calculate modal stresses for any geometry and applying different acoustic power spectral density inputs to calculate the rms stress and the fatigue life. The impact of acoustic induced vibration is primarily dependent upon the acoustic loading and this paper also discusses the challenges involved with accurately calculating the acoustic input loading spectrum shape for a safety relief valve and how it could potentially impact the response/results. This step-by-step approach can facilitate a more realistic and efficient AIV analysis.