Maintainability and reliability of high density polyethylene pipes through experimental and theoretical models

Abstract Our aim is to assess HDPE pipes’ degradation through the failure and reliability modelling by referring only to static tests and models instead of tedious and very costly dynamic ones. For that reason, we were interested in two kinds of specimens, standard ones for tensile test characterization and pipe ones for burst test purpose. The study was conducted over old and newly produced pipes specimens with multilevel notches. Indeed, the specimens were prepared according to the ASTM D 638 and ASTM 1599 respectively. Thus, we were able to establish four concepts of damage models based on the stress, the strain and the energy parameters, to quantify the ageing degradation effect on old pipes, and the burst pressure one, for the notched pipes. Therefore, the obtained results were compared considering neat, old and notched specimens for both the two tests. Then, we showed that the damage is somewhat symmetric around the critical life fraction of 52%. Besides, we concluded that the maintenance of the pipes become obligatory when we get over this point. In addition, the cross-discussion of damage-reliability curves allowed us to assess the limits of the HDPE pipes’ mechanical behavior. Thus, the irregularity of the damage through the wall of the old pipes allowed us to quantify and predict the consumed lifetime of them. These proposed simplified approaches have the advantage to assess quickly the degradation and stability of the studied polymer and decide the right maintence policy regarding the damage-reliability behavior of the studied specimens.