Diagnostic solutions to safeguard hydrogen pipelines

Jens Voss, ROSEN Group

At the moment hydrogen and its use as an energy source in a decarbonized future is top of mind. Not surprisingly, given its properties, which allow it to be used in a variety of ways, transported over long distances and even used to store wind and solar energy. As a final charm, there is an existing pipeline network that crosses the entire European continent and can potentially be used to transport the gas.

Nonetheless there are also significant differences between hydrogen and natural gas that pose entirely new challenges to the system, especially in terms of volume, pressure, and thus maintaining the integrity and safety of pipelines. Therefore, it is important to assess the relevant threats and define an integrity management strategy. This applies to both new and repurposed lines.

Existing codes relate the effects of hydrogen on the grade of steel used. However, there are indications that the effects of hydrogen on pipelines tend to be dominated by the microstructure and chemistry of the steel. In this complex environment of hydrogen embrittlement, the industry needs practical yet safe requirements.

With this in mind, ROSEN is pooling together its decades of expertise in the pipeline business to support the industry as it moves toward a low-emission future.

ROSEN'S TRIAD FOR HYDROGEN

1. Hydrogen Material Testing A solid knowledge of material properties is essential. Therefore, ROSEN’s new hydrogen lab is able to perform the relevant mechanical testing of components and equipment in a high-pressure hydrogen atmosphere. The standard tests include, for example, J-R curves and FCGR testing in air and under hydrogen gas load in order to compare the effects and results in air with those under H2 conditions.

The lab is equipped with 5 autoclaves for standard KIH and exposure testing. They operate in a temperature range of -20 and +200 degrees Celsius to cover the main operational envelope for pipelines. They are connected to an automatic gas mixing unit that allows flexible test gas mixing (hydrogen - H2, methane - CH4, carbon dioxide - CO2, carbon monoxide – CO, and oxygen - O2). The tensile testing machine will be equipped in a comparable way.

The testing scope is rounded off with metallographic examinations and the standard mechanical tests such as tensile and hardness testing.

2. Hydrogen Integrity Assessments Integrity assessment is of great importance, especially in the field of future fuels. The ROSEN Integrity Framework ensures that the correlations between the materials used and the transported medium are understood. "We know the potential threats of transporting future fuels and can assess them with regard to repurposed as well as new pipelines," says Marion Erdelen-Peppler, Vice President - Hydrogen of the ROSEN Group.

The first step is to clarify and aggregate available information with respect to the effect of hydrogen on the structural integrity of steel pipelines and non-metallic pipeline materials. Subsequently a review of the available data and develop methods for the fitness for service assessment of pipelines exposed to hydrogen takes place.

3. Diagnostics: Hydrogen In-line Inspection "Relying on the proven track record of our tool fleet, we realize successful in-line inspection is a key element to assure the integrity of hydrogen pipelines during their operation," states Marion further. "This allows us to support our customers to prepare their natural gas networks for the accommodation of hydrogen."

The industry needs hydrogen engineering guidelines

"Close industry collaboration is incredibly important to work together to move toward a future with a high percentage of renewables in our energy mix. It is also important to maintain a close exchange within the relevant committees in order to keep the practicality of the standards in mind. With this overall package, we contribute to a secure and reliable energy supply," Marion concludes, explaining ROSEN's hydrogen strategy.

ROSEN’s hydrogen laboratory is equipped with 5 autoclaves connected with an automatic gas mixing unit

Cracking specimen in the autoclave