Methodologies for Conversion of New Natural Gas Pipelines to Hydrogen Service in North America

There is an increased interest in the production and use of hydrogen by various industries (utilities, refining, petrochemical, transportation) over the last three years. Applications run from monetizing the molecule for its chemical as well as for its heating and combustion properties, in boilers and fuel cells. As hydrogen projects begin to scale-up across the world, the best distribution solution is via pipelines, even within present natural gas distribution and transmission pipeline systems. A project’s upper hydrogen blending limit will be dictated by the natural gas pipeline owner’s excess driver, compression, and pipeline flow capacities. In this paper we consider a project whereby a greenfield 100% natural gas pipeline would be designed for future conversion to blended natural gas - hydrogen operation and possibly even to 100% hydrogen use. Material selection would have to meet stringent guidelines, including dual certification to ASME B31.8 Gas Transmission and Piping Systems / ASME B31.12 Hydrogen Piping and Pipelines in the US and CSA Z662 Oil and Gas Pipelines / ASME B31.12 in Canada. In addition, the integrity management strategy should be tailored to provide sufficient information for an engineering assessment that maximizes the chances of regulatory acceptance with minimal effort. In this paper, we outline anticipated advisory services for regulatory, engineering, construction support, and integrity management to increase the validity of the service conversion application. Cost differences between natural gas only and hydrogen-ready infrastructure are summarized, including strategies for low-stress design, selection of pipe material grade and wall thickness, and metallurgical considerations for welding, fracture toughness, hydrogen embrittlement and fatigue life management. Finally, additional cost considerations are explored regarding integrity management program development costs, environment and engineering permitting, and consultation.