Live Main Renewed In Town Centre Without Disrupting Gas Supplies

July 3, 2017

Steve Vick International (SVI) contract service teams recently assisted Wales & West Utilities to carry out a major Live Mains Insertion project in the centre of Exmouth.

As part of the ongoing gas mains replacement programme, a 800 metre section of old 14” cast iron gas pipe was inserted with 250mm polyethylene pipe (PE) under ‘live’ conditions, where the main continues to supply gas to the commercial and domestic properties along the street.

The mains renewal was completed section by section with SVI contract service engineers injecting expanding foam into the annular space between the old main and the inserted PE at the end of each section. Live ENDSEAL’s™ were also fitted to stop gas tracking back along the annular space.


Live Mains Insertion offers maximum operational flexibility as customers’ supplies are not interrupted until the individual services are connected, and this can be carried out to fit in with work schedules.

The technique is similar to normal insertion of PE into an old cast iron main except that by using SVI’s LYONTEC™ gland box, the old main is kept live throughout the insertion process and the new PE is gassed up to maintain gas supplies to customers.

Once insertion of the PE pipe is complete, the metallic main is still kept live to supply customers via the annular space until it is operationally convenient to transfer the services to the new main.
Companies using the technique have recorded cost savings of up to 14% compared with dead mains insertion and up to 38% compared with open trench replacement. Wales &West Utilities replace around 400 kilometres of metal pipe a year and 85% of their mains renewals are completed using Live Mains Insertion which the company believes help them to achieve outstanding customer service results.

David Griffiths, Wales & West Utilities Operations Manager said “We know our essential work can be disruptive to homes and businesses and we’re always trying to keep this to a minimum. Using LMI helps us do this. “We used SVI contract engineers to inject expanding foam into the annular space, which allowed us to stop the flow of gas at various sections of the old main once the new PE was in place. The entire project was carried out with the customer in mind, keeping disruption to a minimum.

SVI has been involved in the development of Live Mains Insertion since the technique was introduced in the UK in the 1980s. The company supplies all the equipment and consumables for contractors to carry out projects on mains diameters up to 10”; SVI Contract Service engineers execute LMI for larger diameters up to 18”.

Over 70,000 km of LMI has been carried out in the UK and the technique has also been adopted in the United States, Continental Europe, Scandinavia and the Far East.