Safe Repurposing of Vintage Pipelines for Hydrogen in North America

Hydrogen has been championed as a vital player in the future energy mix needed to achieve net-zero carbon emissions. The deployment of hydrogen at an industrial scale will require pipelines for transportation, and given the many obstacles to new pipeline construction, it appears inevitable that a large proportion of the future hydrogen pipeline network will consist of repurposed existing infrastructure. Conversion strategies require that retrofit pipelines remain operationally safe under the new mode of transportation. From an integrity perspective, the conversion exercise will require understanding the line pipe material’s “DNA” (e.g. grades, hard spots) and assessing the impact of hydrogen on key pipeline mechanical properties (e.g. fracture toughness) and on the tolerance of integrity threats. These threats include those that may already exist from previous hydrocarbon service (e.g. stress-corrosion cracking), those that are directly related to the conversion to hydrogen (e.g. fatigue) and those that are an integral part of a pipeline life cycle (e.g. third-party damages, geohazards). There is currently a lack of clarity within the industry about how to quantify and manage these threats to hydrogen pipelines. How, if at all, should an integrity management strategy for a hydrogen pipeline differ from that of a natural gas pipeline? In order to define the boundaries of the existing North American pipeline network and the starting point for conversion, this paper will conduct an Exploratory Data Analysis (EDA) of (i) the pipeline network’s “DNA” (e.g. diameters, thicknesses, grades, fracture toughness, hard spots, age), and (ii) the pipeline threat and condition attributes (e.g. pre-existing crack threats, crack distribution). This paper will take advantage of the knowledge derived from the ROSEN Integrity Data Warehouse (IDW), a global repository of ILI results and Integrity Management, in order to quantify the characteristics specific to North America. A pragmatic approach to safely repurposing existing pipelines to hydrogen service will be then presented in recognition of the identified regional ‘DNA’ and integrity peculiarities, and in respect to applicable local codes and regulations.