Analysis of the frequency-dependent attenuation of transient pressure waves in plastic pipes

Some recent research proposed to use plastic pipe segments as a dampener in water pipeline systems to mitigate extreme hydraulic transient pressure. However, there is a lack of studies on how the wave attenuation varies with frequency and how different pipe parameters influence the attenuation in typical polyvinyl chloride (PVC) and high-density polyethylene (HDPE) pressure water pipes. This research conducts a sensitivity analysis on the frequency-dependent wave attenuation in plastic pipes using the multi-element Kevin-Voigt (K-V) model. To highlight the effect of pipe wall viscoelasticity, the effect of friction is neglected, and the expression of the frequency-dependent attenuation factor is derived. It is found that, HDPE pipes generally provide higher attenuation than PVC pipes due to the lower elastic modulus of the HDPE material. For typical PVC and HDPE pressure water pipes, the attenuation of low frequency waves (<5 Hz) is moderate, while the rates of attenuation are similar for high frequency waves (>10 Hz). The patterns of attenuation for pipes of different sizes but in the same class (pressure rating) are almost the same, since the ratios of diameter to wall thickness are similar across a given class.