Impact of Temperature and Pressure on Frequency-Dependent Wave Speed and Attenuation in HDPE Water Pipes

Environmental factors in water distribution systems such as temperature and standing pressure can affect the longevity and performance of plastic pipes [such as high-density polyethylene (HDPE) and polyvinyl chloride (PVC) pipes]. While past studies have confirmed that temperature and loading have impact on the mechanical behavior of plastic materials, little research has been conducted to understand how these external conditions affect the hydraulic behavior of plastic water pipes under unsteady-flow conditions. This research investigates the impact of temperature and standing pressure on the dissipation and dispersion of hydraulic transient pressure waves, which are fundamental for hydraulic modeling, wave-based leak detection, and condition assessment in water networks. A series of experiments involving HDPE pipe sections were conducted under controlled conditions. Mechanical creep compliance curves were determined through creep testing at temperatures of 20°C, 30°C, and 40°C and standing pressures ranging from 2 to 8 bar, with pressure increments applied at 15-min intervals. The characteristics of wave dissipation and dispersion of the pipe sections were determined by calibrating the frequency-dependent wave speed and attenuation rate through hydraulic transient testing under water temperatures between 10°C and 19°C and pressures ranging from 2.7 to 3.6 bar. The results demonstrate that, with higher pressure and higher temperature, the frequency-dependent wave speed decreases and the attenuation rate and creep compliance increase. The research contributes to a deeper understanding of the impact of temperature and standing pressure on the hydraulic behavior of HDPE water pipes, which will support better management of water networks and water resources.