Ultra-slim liner solution delivers challenging rail pipe repair
In what is believed to be a UK first, Lanes Group plc has carried out an innovative repair of a siphon pipe beneath a main railway line.
Its sewer rehabilitation and lining division has used a new compact and ultra-thin packer to reach damaged sections beyond a bend in the pipe beneath the Great Western Line near Swindon in Wiltshire.
Amey Rail Division, which is electrifying the line for Network Rail, called in Lanes after finding that groundwater was entering the siphon, a u-shaped pipe taking water underneath the line.
As the pipe was under one of the UK’s busiest railway lines, it was highly desirable to use a no-dig repair system, which would be safer, faster, less disruptive, and less costly.
However, the damage was located beyond a curved section of the 450mm-diameter cast-iron pipe, which prevented conventional lining equipment from reaching the repair site.
The solution, selected by Lanes, was to use a new slim-line cured-in-place-pipe (CIPP) liner installation system.
It allowed two point liners to be moved into position beyond the pipe bend without them rucking up, so they created a smooth and watertight new pipe wall when installed.
Lanes Group Lining Manager Simon Bull said: “To my knowledge, it was the first time this new equipment has been used in the UK. Without it, the pipe could not have been lined.
“We delivered a repair to the standard Amey needed. Water could no longer seep into the siphon, but it could flow unobstructed through the pipe, with no debris snagging points.”
A point liner, also known as a patch liner, is made from resin-impregnated sheets of glass-reinforced plastic (GRP) that are wrapped around a cylindrical rubber tube called a packer.
The packer, along with the liner, is then moved into position in the pipe and inflated with compressed air to push the liner against the pipe wall where it is left to cure in ambient temperature before the packer is removed.
The specialist packer Lanes selected for this project has been designed to be slim and flexible enough to be moved around pipe bends.
However, because it can be inflated to higher pressures – up to 3 bar – it can be used to line pipes with diameters between 200mm to 500mm, a range that would require the use of four different conventional packers.
Simon Bull said: “This new slim-line packer delivers significant benefits that will help us with other challenging point liner installation projects.
“Because of its slim-line design it is ideal for use in narrow manholes and will reduce the number of occasions where we have to dismantle the manhole biscuit to get a packer into a pipe.”
The one-metre-long point liners were installed by a four-person Lanes lining team, supported by a controller of site safety from Amey. No track possession needed.
The siphon was first jetted clean. To do this a portable jetting reel was used to allow 200 metres of hose to be laid from a jet vac tanker parked at the nearest available hard standing area. Water was continuously over-pumped during the installation process.