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Robots deployed to repair London gas mains in world's first

Cisbot2 (1)

First-of-their-kind robots have been deployed to carry out repair work in London’s gas mains.

In what is claimed to be a world first, London’s extensive cast-iron gas main network will be repaired using a fleet of remote-controlled robots. 

Cadent, which operates four of the eight gas networks in the UK, has partnered with American firm ULC Robotics to develop the world’s first robots, known as Cisbots, which are capable of working inside live gas mains.   

Following successful trials, the fleet of four Cisbots will be used by several London boroughs, including Camden, the City of London Corporation, the City of Westminster, Hackney, Hammersmith & Fulham, Islington, Kensington & Chelsea, Lambeth, Richmond upon Thames, Tower Hamlets and Wandsworth. 

The robots nicknamed Cisbot or Cast Iron Sealing-bots, enter gas mains via small pressurised launch tubes, which are purged with nitrogen to ensure there is no flammable gas-air mixture as they go into the live mains. 

The launch tubes only require a small area to access the main and massively reduce the footprint of works compared to traditional methods. Using robots also allows the gas supply to remain uninterrupted.  


Source: Cadent and ULC

Cisbot launch tube deployed on The Strand

Once inside the gas main the robot drills into the bell and spigot joints between pipes, and injects a sealant into the joint under pressure, extending the life of the pipeline by 50 years.  

The Cisbot can travel 450m per launch, with activities only limited by tight bends and valves in the pipes, hurdles which ULC is working to overcome. The large distance the robot travels means entire mains can be serviced with only a few access points required.  

Cisbots can adapt their size to work in pipes with diameters ranging from 400mm to 800mm. 

Cadent head of operations for London James Harrison said: “Cadent and ULC Robotics are spearheading a robotic roadworks revolution with Cisbot”.  

“Cisbots work in the Strand and Oxford Street last year was so successful that we’re now rolling the robots out across our London network, where they’ll help us to do work faster, smoother and more economically than ever before.” 

Trials beneath the Strand resulted in repairs to 185 historically-leaky joints in just seven weeks. This would have taken a team of workers nine months. Other successful trials have taken place under Oxford Street, Regent Street, and Park Lane and more than 5,000m of gas main have been repaired so far.  



ULC UK operations director Sam Wilson said ULC is also working on adapting the technology for other utilities, including a submersible version capable of operating in water pipes. 

“This is an avenue we are trying to pursue,” Wilson said. “The pipes are exactly the same cast iron, but there are different challenges on how the gas or water has affected the inside of the pipe in the hundred or so years it’s been there, different types of scaling, and the issue of sediment being disturbed.”   

Cadent has also launched a specialist engineering apprentice scheme to train new gas engineers in the robotic technology.  

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