Abstract
The calculation of acoustic induced vibration (AIV) for piping downstream of a valve is a critical step in predicting the damage from extreme levels of noise generated by pressure relief valves in flare systems. Three noise prediction schemes are considered for this purpose: International Electrotechnical Commission (IEC) 60534-8-3, the Carucci-Mueller (C-M) formulation for sound power, and an industry valve noise prediction methodology published in the 1980’s. The application of these prediction methods is reviewed utilizing data from a full-scale test system consisting of an NPS6x8 pressure relief valve flowing into a NPS12 tailpipe that is connected through a tee to an NPS20 header. The results show good correlation between the IEC-based predictions and measured internal sound pressure and pipe wall vibration in the AIV frequency region. The industry method provides useful predictions without requiring the level of detailed information needed for the IEC method, whilst the C-M sound power model has limitations when applied to discrete predictions of vibration and strain levels. Observations are also made regarding the relative importance of the FIV contribution to the overall dynamic stresses and associated fatigue life.
