As more and more regenerative energies are being fed into the energy grid, technical demands on the pipes are increasing enormously. The biggest challenge here is the need to harmonize the strongly fluctuating in-feed volumes with the equally varying energy consumption. Accordingly, reliable storage technologies that allow a demand-oriented control of energy supply are extremely important for a successful energy turnaround.
In the power-to-gas area, hydrogen produced by electrolyzers appears particularly useful as a medium for storage and transportation among the currently conceivable storage technologies. The energy tied down in hydrogen can serve for reconversion, it can be fed into the natural gas grid, or it can be used in conjunction with fuel cell technology, for example, in the automotive sector or in household applications. The expected rise in hydrogen utilization will very likely be accompanied by high investments in hydrogen tanks and pipelines. According to the current state of technology, the most economical solution for transporting major volumes of hydrogen is by pipelines.
Up until now, low-strength steel line pipes up to API grade 5L X52 (L360) have been considered suitable for such pipelines and occasionally even standardized for this application. The fact that higher-strength grades have failed to establish themselves in this market has limited the operating pressure of the pipelines and storage tanks to the lower range.
Following extensive tests and investigations, Mannesmann Line Pipe and Salzgitter Mannesmann Forschung are now able to verify the technical suitability of HFI-welded steel tubes up to grade X70 (L485) for hydrogen storage and transportation.
The material's crack resistance was determined in slow strain rate tests (SSRT) under live conditions using hydrogen as the test medium. The round tensile specimens used for this purpose were taken from the base material and the HFI weld. The results revealed no significant influence of the hydrogen on the maximum tensile stress and thus on the strength of the material. The other results, which can be read in the publications linked on the right, also indicate the material's high resistance. This means we are preparing the ground for the continuously increasing economic use of hydrogen.
Further information can be found at www.mannesmann-innovations.com.