H100 Quantitative Risk Assessment for Emergency Purging

Completed

Hydrogen and Fuel Cells(Hydrogen, Hydrogen transport and distribution)

Applied Research and Development

ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering)

Not Cross-cutting

Project Contact
SGN

Network Innovation Allowance

Ofgem

01 June 2024

31 October 2024

ENA months

£131,121

Energy

South East

Network Innovation Allowance

Project Contact, SGN

This technical research project aims to identify, quantify, and mitigate risks associated with performing direct and indirect purging from 32mm to 250mm diameter Polyethylene (PE) pipelines for the H100 Fife Neighbourhood Distribution network. The methodology for addressing this issue involves data collection on leaks from natural gas networks, methods of detection, and diagnosis of leak severity from GS(M)R and SGN database as well as stakeholder workshops. Additionally, prior work, from Hy4Heat, HyPurge, and other relevant work will be reviewed leading to the development of the QRA. The project will consist of the following Work Packages(WP):WP 1:Carry out numerical analysis of the GS(M)R data.Review current guidance on responses to leaks from natural gas networks, methods of detection, and diagnosis of leak severity, etc.Consider the need for rapid response (or otherwise) in detail.Run two workshops for different FCO / ELR teams (one from Scotland Gas Networks and one from Southern Gas Networks, to avoid group think)WP 2:Review prior work, from Hy4Heat, HyPurge, and other relevant work.Develop a QRA for two overarching scenarios: direct and indirect purging.Evaluate event consequences / estimate potential accident frequencies.Estimate the impact of events.Estimate the likelihoods or probabilities.Evaluate the risk. 3. Consider a series of events with reference to:Risk of creation of hydrogen/air mixtures within the pipe.Risk of fire and explosion from any hydrogen cloud created.Risk of relighting leaks.Risk of direct vs indirect purge vs live repair for the smallest leaks.WP 3:Review the output of the QRA to identify scenarios of highest risk.Consider the conditions that give rise to these scenarios, both individually and in comparison, with each other.The outline response to these scenarios will be developed, drawing on the current responses to leakage scenarios with Natural Gas.Reassess the frameworks used in WP1 and WP2.Hold conversations with ELR teams to sense check the mitigations (via Teams).Review the mitigations developed with a broader group drawn from the Peer Review Panel.WP 4:The outputs from the previous WPs will be synthesised - turning data into information. The mitigations will be contextualised to check the numerical outputs and ensure that the QRA matches reality.Analyse the gaps in knowledge that the project identifies and develop work programmes to fill these gaps.Use the Peer Review Panel to ensure broad industry agreement.Disseminate the outcomes of the work to a broad audience within the gas industry, via the Final Report and a Final Workshop / Presentation. The objective of this project is to conduct a quantitative risk assessment (QRA) to identify, quantify, and address the risks involved in carrying out direct and indirect purging operations on Polyethylene (PE) pipelines ranging from 32mm to 250mm in diameter. The project aims to reduce safety risks to the public and customers and facilitate the Networks transition to Hydrogen.

This project aims to conduct a quantitative risk assessment (QRA) to identify, quantify, and mitigate risks associated with direct and indirect purging operations from 32mm to 250mm diameter Polyethylene (PE) pipelines on the H100 Fife Neighbourhood Distribution Network. Current industry practice recommends indirect purging of Hydrogen gas systems in various situations to prevent the potential development of a temporary flammable atmosphere within the pipework. However, indirect purging is a non-routine operation (NRO) for most Gas Distribution Networks (GDNs). Indirect purging carries risks such as nitrogen sourcing and transportation challenges, delivery competencies, over-pressurization, and asphyxiation, which are not present during direct purging. Therefore, it is essential to understand the overall difference in risk between direct and indirect purging for hydrogen systems.

02/04/25