Fundamentals of AIV, FIV, and Random Vibrations in Industrial Piping

A: The hard boundary is acoustic power, not line velocity or ΔP by itself. EI screening is driven by sound power generated at the restriction because that energy excites shell modes and small-bore attachments; Mach number and ΔP are inputs, not the trigger. ISO 10816 is machinery-focused and comes too late in the lifecycle.

A: The gating value is geometry-driven excitation. FIV on small-bore connections correlates with unsupported length and branch configuration; verifying physical layout before forcing flow avoids adding energy into an unknown system. Measuring vibration after excitation or assuming self-damping skips the causal check.

A: The key fraction is percent-level conversion of ΔP·Q to sound power. EI-based screening stems from empirical observation that only a small slice of hydraulic energy becomes broadband noise, yet that slice is enough to drive shell vibration. Equal-power or velocity-only proxies miss the energy balance.

A: The controlling variable is sound power at the source. Diffusers reduce acoustic generation; thicker wall or material change addresses response, not excitation, and insulation affects radiated noise, not shell stress from internal pressure fluctuations.