Effect of Hydrogen on the Reliability of Polyethylene Pipe Materials

Evaluating the existing natural gas infrastructure, compromising nearly three million miles of distribution pipelines, for its capability to transport hydrogen-natural gas blends is essential for the transition to a low-carbon energy future. Notably, over half of these pipelines are made of plastic, with approximately 95% consisting of polyethylene (PE) pipes. Repurposing PE pipes for hydrogen delivery requires a thorough assessment of their compatibility with hydrogen environments. This study investigates the effect of hydrogen exposure on the reliability and lifetime of high-density polyethylene (HDPE) materials. We develop a comprehensive model framework that integrates the Weibull accelerated failure time (AFT) model with various physics-based acceleration models to generate reliability curves. These models account for factors such as temperature and stress under both air and hydrogen conditions. Comparative analysis using existing datasets, which include failure times in both brittle and ductile modes, reveals that the 4-parameter Rate Process Method (RPM) and the 3-parameter Eyring models performed better than other models in predicting low-temperature data. Experimental results demonstrate that hydrogen exposure enhances the reliability of single-edge notched bending (SENB) specimens under creep condition compared to the air environment. These findings provide critical information for the safe and effective repurposing of PE pipeline materials for hydrogen distribution, ensuring their longevity and performance in a hydrogen-rich environment.