Method for determining friction head loss along elastic pipes

Pipes made of plastic materials are generally used in pipelines and the laterals of irrigation systems. Plastic materials such as polyethylene allow significant changes in pipe cross section due to operating pressure, but traditional equations used for determining head loss do not account for this effect. The purpose of this research was to develop an equation for determining friction head loss along elastic pipes. The equation developed is based on the Darcy–Weisbach equation and focuses on pipe cross-sectional variations caused by pressure effects, hence the name pressure-dependent head loss equation (PDHLE). In addition to the parameters required by the Darcy–Weisbach equation, the PDHLE also considers the modulus of elasticity of the pipe material, the pipe wall thickness, and the internal diameter variation due to operating pressure. The PDHLE resulted in high accuracy in determining the friction head loss of elastic pipes.