The climate emergency is one of the biggest challenges humanity must face in the 21st century.
We all need to be involved in the process of moving towards a decarbonized economy. At the same time, the advancing global energy transition faces many challenges when it comes to ensuring a sustainable, reliable and affordable energy supply. For this reason, gas will continue to play an important role in the future energy system. An emphasis on decarbonizing the existing gas infrastructure will inevitably lead to greater penetration of greener fuels, such as hydrogen produced from renewable energy. While the replacement of natural gas with hydrogen and the introduction of hydrogen into modern natural gas transmission and distribution networks creates challenges, there is nothing new or inherently impossible about the concept of hydrogen pipelines. In this regard, the conversion of valuable existing gas grids to hydrogen is increasingly coming into focus for pipeline operators – and thus into the focus of the ROSEN Group.


For pipeline systems that already contain hydrogen, ROSEN has tools that were tested and approved for up to 100 percent hydrogen and 100 bar at ambient temperature, using a special tool setup regarding sealing, material of discs and cups, and H2-proved electronic components, alloys and magnets. At the time of writing, additional testing to ensure reliable tool operations in hydrogen were underway. Using these tools, ROSEN has already performed successful in-line inspection (ILI) runs with a combination of geometry and magnetic flux leakage (MFL) technologies in 100-percent hydrogen pipelines while they were operating normally. Using the customized inspection tool saved the operator from the substantial cost and disruption associated with shutting down and switching to a different fluid for the inspection. With the data collected during the in-line inspection runs, the operator was able to make smarter decisions regarding the integrity of their asset, ensuring hydrogen transport operations that are reliable in all aspects of performance, safety and security.

In addition to preparing existing inspection systems, ROSEN fosters a constant knowledge exchange with operators and experts in order to prepare engineering guidelines and practical procedures for adding hydrogen into natural gas networks with acceptable consequences. In a literature study, ROSEN clarifies the impact of different factors on the interaction of materials with hydrogen and derives mitigation strategies to enhance resistance against hydrogen induced mechanical degradation. ROSEN is currently performing feasibility studies for different industry partners and associations involved in hydrogen transport, all based on our association with the operators of diverse systems worldwide and the engineering and consulting capabilities in pipeline integrity management this has enabled us to accumulate – not to mention our understanding of the capabilities and limitations of in-line inspection technology.

ROSEN has integrated this experience and integrity subject-matter expertise with appropriate inspection technologies into a comprehensive hydrogen integrity framework to help pipeline operators in de-risking the process of converting existing natural gas infrastructures to hydrogen and thereby contributing to a safe and efficient lifetime extension of existing assets into a low-carbon future.


This approach is founded on the extensive research that has already been completed on issues such as material susceptibility to hydrogen-induced embrittlement and accelerated fatigue cracking and on the technologies that are already available to map material properties, geometry and deformation features where stress levels are elevated as well as features that may be starting points for fatigue cracks.

ROSEN has worldwide experience in successfully implementing its multidisciplinary crack management framework to help global oil and gas operators to reduce uncertainty and improve decision-making when faced with cracking threats. Although knowledge gaps still exist, for example surrounding the exact magnitude of the threat posed by hydrogen partial pressure in gas/hydrogen blends, integrity management of converted hydrogen pipelines follows an approach similar to other cracking mechanisms.


Figure 1 – ROSEN's hydrogen integrity framework

Current conversion feasibility studies and initiatives are primarily focused on the left part of the framework, looking at identifying threats, material compatibility, code compliance, or code amendment and operational compatibility. Accurate and reliable information on our assets and an efficient way to store and retrieve it will become more important, feeding into the threat analysis.

Looking at, for example, “Threat Analysis,” robust knowledge of material properties and any significant local variations in properties forms the basis of any fitness-for-hydrogen assessment. In recent years, the ROSEN Group has introduced a holistic approach to pipeline material verification, incorporating review and alignment of existing records, unique material property ILI technology, in-situ field examinations, material testing, and industry expertise to ultimately establish a complete and thorough knowledge of pipeline material properties.

This allows for the efficient selection of combinations of inspection and testing technology and, together with the threat analysis, helps to manage expectations regarding the outcomes of such an inspection. Truly understanding what to look for and what technology is best to use results in being able to identify “the needle in the (data) haystack” and define the most effective future mitigation against threats associated with H² service. In the end, these findings will need to be reflected in an updated risk assessment that serves as input for future integrity management plans and processes.


A holistic approach that – like the presented hydrogen integrity framework – involves the identification and quantification of threats along with appropriate mitigation and management, enables the safe, economic and successful introduction of hydrogen into the natural gas network.