Zhang Wei

Safe and efficient storage and transportation are preconditions for the large scale development of hydrogen energy. For scenarios with long distances and large transportation volumes, pipeline hydrogen transportation is the best choice. Due to the significant differences in structure and properties between hydrogen and natural gas, there is a lack of data support for directly using HDPE gas pipelines to transport hydrogen, and there are certain risks. This paper studies the microstructure of special materials for gas pipelines and the hydrogen permeability, designs and develops a set of test device that uses hydrogen as the medium and can evaluate the long-term hydrostatic pressure strength of HDPE materials according to ISO 9080. The YGH 041T special material for gas pipelines produced by Sinopec is selected for the test to explore the influence of hydrogen on the long-term strength of HDPE materials.

In this paper, by choosing a four parameter model, the relationship among test temperature, test pressure, and failure time in a hydrogen environment is discussed. The obtained data are fitted by multiple linear regression to determine the long-term hydrostatic pressure strength of YGH 041T in a hydrogen environment. The test results show that: (1) Hydrogen permeability is related to the crystallinity of the material. The higher the crystallinity, the lower the permeability. Under normal temperature and standard atmospheric pressure, the hydrogen permeation amount per unit thickness of PE100 grade material is only 10-14(cm³/(cm²d Pa)); (2) Under the same test temperature and test pressure conditions, the failure time of the test sample is affected by the test medium. The failure time with water as the medium is longer than that with hydrogen, and the higher the test temperature or test pressure, the more obvious the difference in failure time; (3) In the tests with hydrogen as the medium, at three temperature conditions of 20°C, 60°C, and 80°C, there is no inflection point within 8760h, and the failure mode of all samples is ductile failure; (4) Through multiple linear regression fitting of all data, the 50 year long-term hydrostatic pressure strength σ(hydrogen) is lower than σ(water), but the extrapolation curve of hydrogen is still above the PE100 standard curve.