The Project

Northern Gas Networks are leading the H21 project on behalf of the other Gas Distribution Networks within the UK to provide the safety based evidence for a 100% Hydrogen conversion in the below 7 bar GB gas distribution network.  The next stage is to address the strategic evidence at a network level.  The current H21 (Phase 1a and 1b) is looking at the performance of the existing gas network at asset level and establish the background performance of assets and the behaviour of hydrogen in our natural surroundings.  However, there remains the need to research and understand the network performance and operations when converting to 100% hydrogen.

The project is the construction of a new hydrogen test facility to trail gas industry operational and maintenance procedures with 100% hydrogen.  This is to further develop an existing hydrogen test facility to be able to simulate the various operations on a distribution network, to ensure they can be performed in a similar manner.

Sonae (UK) were appointed to carry out the commissioning the new hydrogen test facility on behalf of Northern Gas Networks.  All pre-commissioning checks to be carried out by the E&I installer.


SONAE were responsible for supplying both the NRO documentation and competent persons to control and execute the changeover in line with the networks SCO 5 requirements.

Provision of SCO 4&5 competent persons to carry out the end to end checks and wet commissioning of the complete E&I installation under a controlled NRO procedure.

The support consisted of conceptual and detailed design review in conjunction with all parties to establish buildability, maintainability and sequencing of the works to minimise or mitigate interruption to live processes while maximising on any synergies with other disciplines or departments including quality assurance checks during the construction phase.

Final walkdown site visits were carried out with the Northern Gas Networks Project Engineer and other interested parties such as NGN ARM and NGN Maintenance to ensure snagging and asset tagging works complete to the satisfaction of NGN, obtain user acceptance of the completed works and carry out a ‘lessons learnt’ exercise to identify possible preferences or improvements for future works.


Project records were produced and submitted at key stages throughout the project including support documentation for G17 part D,E and F sign off such as signed red-line marked up as-built drawings, dead and live test commissioning results, instrument pressure test certificates and vendor FAT and SAT documentation where applicable.

All final handover records were submitted to the Northern Gas Networks in both electronic format via A-site media document control system and hard copy format.

Health & Safety

All works were carried out under a controlled PTW in accordance with Northern Gas Networks SCO (Safe Control of Operations) management procedures.


September 2019