Weybridge, Line stop

The brief

Affinity Water needed to install two isolation valves and a fire hydrant on a live water main in Weybridge. All three fittings required the main to be opened up at their respective tie-in points, which, on a live main at mains pressure, isn’t something you can do without first isolating the working section.

Shutting the main down for the install would have meant draining a section of the network, switching affected customers onto alternate feeds where possible, and then the reverse process on reinstatement. A lot of effort and customer disruption for what is, at its core, a standard network upgrade.

Our approach

Line stop. A line stop involves fitting a temporary plug inside the main, under pressure, to isolate the section being worked on without depressurising the wider network. The rest of the main stays in service, customers stay in supply, and the working section can be opened up, worked on, and closed back up with no shutdown.

With the line stop in place, the two valves and the hydrant were cut into the main and jointed up. Line stop equipment was then removed, the main returned to full pressure, and the new fittings commissioned onto the live network.

Outcome

Three new network fittings installed, main never out of service, customers unaffected. For broader technique context see our line stopping capability page. The service context sits under water mains repair and maintenance for water companies.