Influence of Service Life on Physical and Mechanical Characteristics of Polyethylene Pipes

An experimental evaluation of the decrease in actual physical and mechanical characteristics of low pressure polyethylene (HDPE) pipes depending on the duration and conditions of their operation has been conducted. To assess the impact of operational factors on the pipe characteristics, the following parameters were determined: tensile elongation and tensile strength, thermal stability (induction period of oxidation (IPO) of the material), and degree of crystallinity. It was found that, after prolonged operation of HDPE pipes compared to the initial normative values, the most significantly affected parameters are the tensile elongation and the induction period of oxidation. Moreover, the changes in tensile elongation and IPO parameters have a similar nature in terms of the loss of properties, indicating a correlation between them. The most sensitive indicators for predicting the service life of HDPE pipes are the tensile elongation and the induction period of oxidation. On the basis of the data obtained, it seems promising to monitor the IPO value when determining the technical condition of polyethylene pipes. A calculated forecast of the service life of polyethylene pipes based on reaching their ultimate state has been performed.