Steel producer Dillinger and Saarland University are cooperating to protect pipelines from damage caused by H₂. Due to so-called 'hydrogen embrittlement', H₂ accumulates in the pipeline material and cracks can form. Over the next three years, Dillinger is funding two chairs at Saar University with a total of €800,000 as part of a research project.
Green hydrogen is intended to make energy-intensive companies, such as those in the steel industry, climate-neutral. But hydrogen causes materials that come into contact with it to become brittle. Hydrogen pipelines could be damaged as a result. Scientists at Saarland University are therefore working with Dillinger to find a standardized industrial test method that examines the sensitivity of steel to hydrogen.
Prof. Chrisitan Motz: "The core problem here is so-called 'hydrogen embrittlement'. This well-known phenomenon primarily affects high-strength materials such as pipeline steel or steel wires in prestressed concrete bridges. When hydrogen accumulates in the material, the strength of the material decreases and minute damage and cracks can occur that can seriously endanger the pipeline or bridge."
Until now, damage from hydrogen embrittlement has rarely been a problem. Hydrogen accumulates at welds or through corrosion in small amounts that can cause damage only very slowly. If green hydrogen is seen as the energy carrier of the future for industrial processes, the magnitudes of hydrogen, which mainly occurs in pipelines, will also change.
Scientists develop test methods
Over the next three years, the scientists:inside want to find out which test methods are efficient. They also want to investigate how hydrogen is transferred into the material via a standardized path. These "loading methods," as Christian Motz says, are very different. Hydrogen can be introduced into the material electrochemically or by pressure charging. To do this, hydrogen is pressurized to 200 bar at 200 to 300 °C, he says.
The chair of Professor Hans-Georg Herrmann investigates the damage caused by hydrogen and evaluates the steels. Computed tomography (CT), an X-ray technique, is used to look inside objects without destroying them. It can be used, for example, to analyze cracks and pores caused by the hydrogen.
"We use a unique, state-of-the-art research device that can image structures as small as 50 nanometers. This is about a thousand times smaller than the thickness of a human hair," explains Jonas Fell.
In combination with a second system, this allows the smallest damage in the steels to be made visible over several orders of magnitude, from the millimeter range to the nanometer range. Based on this comprehensive analysis, the researchers can evaluate the suitability of the steels for use in future pipelines.
Further plan for the future
The non-destructive method can be used to observe live changes over time, such as the formation of cracks and their growth. To this end, the project will develop a special test setup with which the steels can be mechanically stressed under the influence of hydrogen and simultaneously observed using X-ray technology.
Wolfgang Schütz, Head of Research and Development Products at Dillinger: "We are convinced that the results from the research work will give us important impetus to develop optimized steel designs for the transformation and the age of 'green' hydrogen."
"The cooperation with Saarland University makes us even faster and more flexible and gives us competitive advantages in the promising market for pipelines."