Session: 09-02-01 Repurposing pipelines for H2 transportation

Paper Number: 132411

132411 - Opportunities and Challenges in Repurposing Canadian Natural Gas Transmission Pipelines for Hydrogen Service – A Regulatory, Standards, and Technical Exploration 

Abstract: 

This paper addresses the opportunities and challenges associated with repurposing Canadian natural gas transmission pipelines for hydrogen/natural gas-hydrogen blend service, offering valuable insights for pipeline operators, particularly in Alberta. The focus is on identifying pipeline segments with higher conversion potential, understanding challenges from existing codes and regulations, and assisting standards committees in identifying and addressing gaps.

The paper's scope begins with a comprehensive overview of Canadian natural gas transmission pipeline design and materials, reviewing data specific to Albertan intraprovincial pipelines. Analysis of characteristics such as pipe hoop stresses, material of construction (primarily carbon steel and polyethylene pipe), pipe vintage, and steel grade will be explored. Notably, a majority of carbon steel pipelines in Alberta use low- to medium-strength grades, with over two-thirds operating at low hoop stresses, potentially meeting hydrogen service requirements per standards such as ASME B31.12. Commentary on hydrogen's potential impact, considering these characteristics, will be provided.

The discussion then shifts to challenges existing transmission pipelines may face in meeting hydrogen service requirements due to gaps in applicable standards. Highlighting potential challenges rather than an exhaustive list, the paper aids in the required engineering assessment (EA) per CSA Z662:23 that is cited in Canadian federal and most provincial pipeline-related regulations. The 2023 edition of CSA Z662 includes additional provisions specific to hydrogen gas service through Clause 17, applicable to both new pipelines designed for hydrogen or hydrogen blend service, as well as conversion of existing pipelines. According to this standard, operators are required to conduct EA that encompass various topics such as material selection and pipeline design to address the potential adverse effects of hydrogen on pipeline materials. CSA Z662 also references ASME B31.12 as an additional guidance document for hydrogen service, which is widely regarded as the applicable standard for high-pressure hydrogen pipelines. However, pipelines originally constructed for natural gas service are unlikely to meet the minimum requirements for hydrogen service outlined by ASME B31.12. For example, the maximum allowed pipe hoop stress, minimum Charpy absorbed energy, maximum hardness, and maximum specified minimum yield strength (SMYS) and ultimate tensile strength (UTS) stipulated by ASME B31.12 can be more stringent than those specified in CSA Z662 and CSA Z245.1. ASME B31.12 also requires the evaluation of parameters that typically rely on data not commonly available for pipelines designed for natural gas, such as Charpy absorbed energy in the pipe welds and heat-affected zone (HAZ). With the lack of readily available data and the specification to obtain pipe samples every 1.6 km stipulated by ASME B31.12, operators considering the conversion to hydrogen service may face challenges in complying with all specifications in ASME B31.12. Pertaining to low-pressure, low-stress natural gas distribution pipelines made of carbon steels, further evaluation is needed to determine the necessity and feasibility of the aforementioned requirements. Additionally, this paper addresses components within pipeline systems such as fittings, flanges, valves, compressor equipment, and meters.

Acknowledgement

The findings in this paper are based on multiple research projects led by DNV, with funding provided by CSA and ASME.

Presenting Author: Randy Dinata DNV

Presenting Author Biography: Randy Dinata is a senior engineer within Hydrogen and Modelling team at DNV. His area of expertise includes hydrocarbon/CO2/hydrogen processing, transportation and storage, technology assessment, digital technology development as well as R&D and JIPs stewardship. He is currently involved in various hydrogen projects such as designing the compression system and storage for a green hydrogen pilot project, assessing pipeline capacity for hydrogen and CO2 transport for a blue hydrogen techno-economic assessment, developing natural gas – hydrogen blending station design, and evaluating the current state-of-the-art hydrogen technologies from production to end use. He holds both BSc and MSc degrees in petroleum engineering and has been involved in numerous large-scale capital projects and operations such debottlenecking and expansion of a $1.7 Billion underground gas storage processing facility.

Authors:

Randy Dinata DNV
Shane Finneran DNV