Natural aging mechanism of buried polyethylene pipelines during long-term service

Currently, accelerated aging tests are widely used to study the aging process of polyethylene pipelines. However, this approach can only simulate one or several main influencing factors in the natural envi-ronment, which are often quite different from the actual environment of the buried pipelines. In this study, five types of PE80 buried pipelines in service for 9-18 years were taken as the research object, while new PE80 pipelines were taken as the reference group. The aging process and mechanism of polyethylene buried pipelines were studied through mechanical and chemical property tests and microstructural analysis. The results showed that the pipeline exhibited cross-linking as the main aging mechanism after being in service for 0-18 years. The aging degree and law of the inner and outer surface of the pipeline were compared, and the observed mechanism of both surfaces was explained. After 18 years in service, the elongation at the break of the pipe decreased by 16.2%, and the toughness of the matrix in the main collapse area of the tensile sample was the fundamental reason responsible for changes in the mechanical properties. Finally, after 18 years in service, the oxidation induction time of the pipeline was 25.7 min, which was 28.5% higher than the national standard value. There were no potential safety hazards during continuous long-term service. The results of this paper provide reference data and theoretical guidance for the aging process study of buried polyethylene pipelines.(c) 2023 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Automated summary

This study investigates the aging process and mechanism of polyethylene buried pipelines through mechanical and chemical property tests and microstructural analysis. The results reveal that cross-linking is the main aging mechanism after the pipeline has been in service for 0-18 years. After 18 years in service, the pipeline shows a decrease in elongation at break by 16.2%. The oxidation induction time of the pipeline is 25.7 minutes, which is 28.5% higher than the national standard value. The findings from this study provide reference data and theoretical guidance for the aging process study of buried polyethylene pipelines.