Analysis of a HDPE flanged connection with a time and temperature dependent constitutive behavior

High density polyethylene (HDPE) piping systems are used extensively in both industrial and societal infrastructure. However, their performance is sometimes impacted due to leakage through flanges, especially HDPE pipes with large diameters. Many factors affect leakage, including stress relaxation the material ambient temperature effects. Hence, this study investigates effect of on a flanged connection steel backing rings. It incorporates effects assesses degradation time by means finite element analysis (FEA). The dependent mechanical properties determined experimentally tensile, compression testing conducted at various temperatures under isothermal conditions. constitutive behavior modeled using nonlinear visco-elastic plastic three network model (TNM), which predicts markedly well. calibrated TNM FEA investigate (23, 40, 60 80 °C) conditions over service one year. results reveal that can experience all insufficient bolt preload. also found occurs prematurely as increases. To simulate realistic scenario resembling an above ground system, annual profile for selected geographic location was prescribed year period. Based results, several re-torqueing plans were explored suggestions made best practice preventing life connection.