Lifetime prediction of natural gas polyethylene pipes with internal pressures

The purpose of this study was to propose a lifetime prediction model of aging natural gas polyethylene (PE) pipeline with various internal pressures by thermal-oxidative aging (TOA) test and oxidative induction time (OIT) test. By using a pressured natural gas PE80 pipe under the condition similar to actual urban natural gas working condition, an improved TOA experimental set-up was built, and had been used for accelerated TOA test of pressured PE pipes at different test temperatures. By using dynamic curve linearization method and based on Arrhenius fit of the data, an empirical lifetime prediction model of thermal oxidative aging law for PE pipes was developed to extrapolate lifetime of PE80 pipes with internal pressures. The results show that under the test internal pressure of 0.1 MPa, 0.2 MPa, 0.3 MPa, and 0.4 MPa, the lifetimes of aging PE gas pipes with internal pressure are 14%, 24.5%, 36.1%, and 41.6% shorter than those without internal pressure.