Scaling the vibrations of water pipes: Application to industrial case studies

A scaling approach for the vibrations of water pipes was proposed in the ASME PVP 2005 Conference. Using a single hole orifice in non-cavitating conditions as a reference noise source, the vibrations of a piping system were estimated on the basis of plane wave propagation for the acoustics, and on the basis of vibrating beams for the structure. The scaling of the velocity Power Spectral Density (PSD) of a pipe is then a function of the pressure drop of the device considered, of the inner and outer diameters of the pipe, of the flow velocity, of the support spacing and of the densities of steel and water. The present paper describes the application of the scaling approach to industrial case studies: velocity PSD were measured on a sample of piping systems with pressures varying from 3 to 100 bars, with flows varying from 30 to 1000 m ³/h and with hydraulic powers varying from 10 to 200 kW. The sources of vibrations were orifices, globe valves and butterfly valves in turbulent or cavitating regimes, and centrifugal pumps operating at nominal or partial flow regimes. In most cases, the measured data match the scaling law based on the single hole orifice noise, as an order of magnitude. A closer look reveals that different sources of vibrations exhibit recognizable patterns; the partial flow regime of a centrifugal pump generates a velocity PSD different from the nominal regime, and the cavitation of a globe valve generates a velocity PSD very different from the one generated by the cavitation of a single hole orifice. Typical non-dimensional spectra are proposed for each type of noise generating device.