Safety Considerations for the Transport of Hydrogen Gas in Line Pipes and Induction Bent Pipes

With increasing impact of hydrogen-based economy it is necessary to consider relevant hydrogen embrittlement effects and risks resulting from it. As higher gas pressures are in discussion, the use of higher steel strength levels as compared to existing pipelines appears reasonable. Clarifying the product requirements is necessary for safe operation. Lately, the interaction of pressurized hydrogen gas with steel has been studied more detailed. This allows more precise safety considerations for the transport of hydrogen gas. The results of laboratory trials of different semi-finished products (medium and large diameter line pipes, induction bent pipes) exposed to hydrogen gas will be used to clarify this point. Several laboratory test methods were selected, allowing to focus on local effects of hydrogen enrichment in conjunction with mechanical loads. Challenges when testing in high pressure hydrogen environment result mainly from the safety aspects to be respected, but also from precautions required to achieve reproducible test conditions and to avoid unwanted system contaminations. Substantiated test results indicate excellent behavior of the materials tested in terms of ductility and fracture toughness in high pressure hydrogen applications; all relevant ASME criteria for material selection are fully met. To support the ongoing discussion regarding hydrogen testing protocols and relevant material properties (toughness parameters) in both, qualification of components and design of pipelines, Salzgitter and its Steel Processing business units are planning further extended R&D studies.