Feeder 5 is a key pipeline that runs from Bacton, the Norfolk North Sea Terminal for National Gas, through East Anglia into the south of London, and through to Kent. A significant section of pipeline that serves a huge area with power generation, industry and homes and businesses dependent on its supply for power and heat. During 2024, National Gas scheduled the largest body of work the region had ever experienced, and possibly the largest in the company’s recent history for pipeline improvement works and they had a target of getting it completed before the end of 2024.

The works involved an exceptionally detailed NRO (Non-Routine Operation) outlining how to safely isolate Feeder 5, which spans over 132 kilometres or roughly 82 miles of pipeline. The safe isolation of this pipeline and the resulting outage was successfully delivered by United Infrastructure working collaboratively with National Gas. There were long days, weekends, and night shifts to deliver key milestones such 24-hour operation at Chelmsford compressor station to ensure a safe and timely network isolation.

The Feeder 5 project was vast, and it is National Gas’ biggest single feeder outage to date and the core construction works were completed within a six-week period with significant work either side to safely isolate the system, well ahead of schedule. This meant that the gas system could be restored by mid November 2024, before the cold weather arrived.

Executing a project of this scale within such a condensed timeframe came with significant challenges. At Braintree, substantial movement in one of the isolation joints required immediate response, leading to a continuous 26-hour shift to resolve the issue. Similarly, at Abridge and Luxborough Lane, design adaptations were required to address future ground settlement risks, which UI successfully implemented in collaboration with National Gas.

At Horndon, managing the interface between Cadent and National Gas operations on a shared site required proactive planning and clear work area segregation to ensure efficient progress. Chignal St James presented difficulties due to below-ground pipework encased in concrete, necessitating a revised sequencing plan to mitigate potential delays.