f H21 Phase 2A: Finding and Accessing Leaks

In line with the UK government’s de-carbonisation strategy, Northern Gas Network’s (NGN) H21 project aims to demonstrate the feasibility of converting the existing <7barg gas distribution network to 100% hydrogen. After conversion of the gas networks, hydrogen is transported from various sources through new and existing gas networks to industrial and domestic customers.
Following progress on Phase 1 of the H21 programme, Phase 2 was proposed to build on the knowledge acquired to provide further quantified safety-based evidence on the suitability of the GB networks to transport 100% hydrogen. Phase 2 consisted of a number of Project Phases. Phase 2a evaluates network components and operational procedures, identifying which of these are suitable for a 100% hydrogen network and those that may require adjustments. Firstly, a review of all NGN operating procedures was conducted by HSE Science and Research Centre (HSE S\&RC). From this review, various recommendations for changes to some procedures were made for their application to a hydrogen network. Of these proposed changes, some required more investigation and demonstration. To achieve this, a gas demonstration network was built at DNV Spadeadam Research and Testing to accommodate full scale network parameters and typical network components. A Master Test Plan (MTP) was subsequently developed by NGN in collaboration with the HSE R\&SC and DNV to address various aspects of existing network procedures and operations including:
♦ Emergency Response and bad practice demonstrations
♦ Finding leaks
♦ Accessing leaks
♦ Assessment of repair techniques
♦ Live gas operations
♦ Isolation techniques
♦ Commissioning and decommissioning activities
♦ Pressure regulation and maintenance procedures
♦ Pressure and flow validation
Each of these areas of testing and assessments were then divided in individual tests or tasks and identified with a unique ID name.
The current report details the work conducted in the H21 testing facility WBS5 downstream of the H21 demonstration facility, herein referred to as the “Microgrid”, in relation to finding and accessing buried leaks. The programme included consequence tests where live leaks and pockets of gas under various ground surfaces were ignited, manned live leak finding operations (barholing/rockdrilling) and accessing leaks on gas saturated ground locations over an isolated section of leaking pipe.
This report details the experimental set-up, instrumentation (if any) and test procedure used in Section 3; the results and main observations in Section 4, followed by interpretation of results and conclusions in Section 5. Appendixes at the back of the document contain photographs, diagrams and further details for each test.
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.