Influence of Pipe Material and Liquid Properties on Water-Hammer Wave Propagation and Transient Pressure Response

Water-hammer transients in pressurized pipelines are governed by the coupled compressibility of the liquid and the elastic response of the pipe wall. This study quantifies the sensitivity of transient pressure responses to variations in pipe material, system geometry, and liquid properties using a one-dimensional Method of Characteristics (MOC) model incorporating a convolution-based formulation of unsteady friction. The model is applied to an experimental copper-pipe system under laminar and turbulent flow conditions. A one-factor-at-a-time (OFAT) sensitivity analysis is performed by independently varying selected parameters by ±5% and ±10%, including Young’s modulus, Poisson’s ratio, pipe-wall thickness, internal radius, liquid density, bulk modulus, and kinematic viscosity. The results show that liquid density, liquid bulk modulus, and pipe Young’s modulus significantly affect pressure-wave celerity and the temporal evolution of the transient response. Pipe internal radius has a pronounced influence on the pressure response, while the effects of viscosity and bulk modulus become more significant under turbulent-flow conditions. Combined variations in material, pipeline geometry, and liquid properties yield pressure-wave celerities ranging from approximately 1159 to 1479 m/s, demonstrating the substantial influence of input-property uncertainty on predicted transient behavior. The OFAT results are further analyzed using multiple-valued logic (MVL) decision trees and classification and regression tree (CART) models to identify dominant parameter–response relationships and threshold values. The findings highlight the importance of accurately characterizing pipe-material and liquid properties for reliable water-hammer prediction and the assessment of pressurized pipeline systems.