A Lifetime Prediction Method of Pressured Gas Polyethylene Pipes by Thermal-Oxidative Aging Test and Tensile Test

Polyethylene (PE) pipes have the advantages of low weight, corrosion resistance, high impact resistance, and superior flexibility, and have been widely used for various urban gas engineering. With the increase of service life, the aging of PE pipes has become a safety issue that needs to be solved. So far, the aging performance of PE pipes are researched at home and abroad, but there are few reports on the aging performance of PE pipes under different pressures which are similar to actual urban gas working condition. Therefore, an accelerated aging test of gas PE pipes under different pressures was carried out by a thermal oxygen aging experimental setups. After that, mechanical properties of the aged PE pipes were tested by a tensile test. Then, based on the tensile test's results, empirical equations of pressured urban gas PE pipes were got by Arrhenius fit of the data, and finally, a life prediction model of pressured urban gas PE pipes was proposed. The results show that tensile strength (TS) of the aged gas PE pipes reduces with the increasing internal pressure. The lives of the PE gas pipes with internal pressure of 0.1 MPa, 0.2 MPa, 0.3 MPa, and 0.4 MPa are 10%, 22.4%, 34.7%, and 44% shorter than those without internal pressure, respectively. This life prediction method is not only suitable for pressured urban gas PE pipes, but also for other plastic pipes in similar environments.