Tools · Piping & flow
AIV sound power level
High-pressure gas letdown through a valve, PSV or orifice radiates intense noise inside the downstream pipe. The sound power level is step one in screening for acoustic-induced vibration fatigue.
Sensitivity: change in PWL if you double the flow, or halve the pressure drop.
The formula
PWL = 10 · log10[ W² · (ΔP / P1)3.6 · (T / Mw)1.2 ] + 126.1 + K
W in kg/s, T in kelvin, ΔP = P1 − P2; K is 0 for subsonic and 6 dB for sonic (choked) flow. This is the Carucci–Mueller correlation, built from field data on piping failures downstream of pressure-reducing devices. It's the basis of the sound power step in the Energy Institute AIV screening method.
Notice how strongly flow drives it: PWL rises with 20·log(W), so doubling the flow adds 6 dB. Splitting a large letdown across stages, or across several smaller devices, is one of the main design levers.
What this does not do: the likelihood-of-failure assessment. That also depends on the downstream pipe diameter and wall thickness, the distance to the nearest branch or discontinuity, branch connection types and sound attenuation along the line, all defined in the Energy Institute guidelines. Use this to see quickly whether a source is quiet or loud, and the full method for the assessment.
Method & sources
What it calculates
- Carucci–Mueller correlation: PWL = 10·log10[W²·(ΔP/P1)^3.6·(T/Mw)^1.2] + 126.1 + K (W in kg/s, T in K).
- K = +6 dB for sonic (choked) flow; choking when P1/P2 ≥ ((γ + 1)/2)^(γ/(γ − 1)).
Assumptions & limits
- Sound power at the source only. The likelihood-of-failure assessment (pipe D/t, distance to discontinuities, branch type, attenuation) follows the Energy Institute guidelines.
- Eisinger (1997) gives a D/t-based design limit for comparison.
Verified: 20 kg/s from 50 to 10 bar a at 40 °C, Mw 19 (choked) gives 169.2 dB, matching Python.
Sources
- Carucci, V. A. and Mueller, R. T. (1982). Acoustically induced piping vibration in high capacity pressure reducing systems. ASME paper 82-WA/PVP-8
- Energy Institute (2008). Guidelines for the avoidance of vibration induced fatigue failure in process pipework, 2nd edition ↗
- Eisinger, F. L. (1997). Designing piping systems against acoustically induced structural fatigue. Journal of Pressure Vessel Technology 119(3), 379-383 ↗
- Gas Processing & LNG (2020). Calculate likelihood of piping failure from high-frequency acoustic vibration ↗