Hydrogen energy has been vigorously developed in recent years, but excessive transportation and storage costs have become a key issue in restricting the development of hydrogen utilization. Blending H2 into existing natural gas long- distance pipelines is the potential best way to transport hydrogen on a large scale, cost-effectively and efficiently. However, H2 can induce hydrogen embrittlement of pipeline steel, which seriously restricts the safe operation of hydrogen-blended natural gas pipelines.