When the specification calls for CIPP, one of the first technical decisions is how the liner will be cured. UV pipe lining uses ultraviolet light instead of hot water or steam to harden the resin, and that difference in cure method changes the installation sequence, the site footprint, and the range of projects where the liner performs best. Insituform manufactures iPlus Glass UV, a glass fibre-reinforced CIPP liner designed specifically for UV-cured rehabilitation, and part of a wider CIPP solutions range we have been developing since we invented CIPP in 1971.
How UV Cure Hardens a CIPP Liner
In a thermally cured CIPP installation, hot water or steam is circulated through the liner to activate a thermoset resin. The process works, but it requires boilers on site, water supply, and extended cure windows depending on liner thickness and ambient conditions.
UV pipe lining replaces that with light. The resin system used in a UV-cured liner is photo-initiated, meaning it polymerises when exposed to ultraviolet light at a specific wavelength. A UV light train is pulled through the liner at a controlled speed, activating the resin section by section. As the light passes, the resin hardens into a rigid thermoset composite bonded to the host pipe wall.
The result is the same: a fully structural, jointless pipe-within-a-pipe. But the way you get there is faster, uses less energy, and requires significantly less equipment on site. For a broader look at UV CIPP lining and its applications, we have covered the detail separately.
Why Glass Fibre Is the Reinforcement for UV CIPP
Glass fibre is not just a material choice for UV-cured liners. It is a functional requirement.
Unlike polyester felt used in thermally cured CIPP, glass fibre is light-transmissive. That means UV light can penetrate through the full wall thickness of the liner, ensuring complete and consistent cure from the inner surface to the outer wall. Without that light transmission, UV curing simply does not work reliably.
Glass fibre reinforcement also delivers superior mechanical properties. iPlus Glass UV uses less resin than a standard felt liner while achieving equal or greater structural performance. The thinner wall profile that results from this is a genuine engineering advantage: it preserves more of the host pipe’s internal diameter, maintaining hydraulic capacity in flow-sensitive gravity networks.
We also supply iPlus Glass RF, a variant with a reinforced outer foil that removes the need for slide foil on diameters up to 400mm. For engineers specifying across mixed-diameter projects, both products sit within the same iPlus technology family.
From Pull-In to Cured Pipe: The UV Installation Sequence
The installation sequence for UV pipe lining is different from a thermally cured CIPP installation, and understanding how it works matters when writing a specification.
- Liner delivery. iPlus Glass UV is manufactured at our Wellingborough facility and delivered to site resin-impregnated, ready for installation. It can also be shipped dry for on-site impregnation.
- Pull-in. Unlike felt CIPP, which is typically installed by inversion, iPlus Glass UV is pulled into the host pipe. The pull-in method reduces material waste and allows precise positioning within the pipe.
- Inflation. Once in position, the liner is inflated against the host pipe wall using air pressure, conforming to the pipe profile.
- UV light train. A UV light train is pulled through the inflated liner at a controlled, calibrated speed. The light activates the photo-initiated resin, curing the liner section by section into a rigid composite.
- Cured pipe-within-a-pipe. The finished product is a jointless, fully structural thermoset liner bonded to the host pipe. Post-cure CCTV inspection confirms fit, cure quality, and structural integrity.
iPlus Glass UV covers diameters from 150mm to 1,200mm, handles soft bends up to 30 degrees, and achieves typical shot lengths of up to 200 metres. It is compatible with any host pipe material, with an effluent temperature tolerance of 75°C and a pH range of 4 to 10. Insituform manufactures the liner system only. UV curing equipment is sourced through specialist third-party providers.
Where UV Cure Earns a Place on a Specification
UV pipe lining is not the right answer for every CIPP project, but there are clear conditions where it outperforms thermal cure.
Flow-sensitive gravity networks. The thinner wall profile of glass fibre pipe lining preserves hydraulic capacity where every millimetre of internal diameter counts.
Tight delivery windows. UV curing is faster than thermal curing because there is no water heating, no cool-down period, and no dewatering. That matters on projects where road closures or service outages are time limited.
Noise and footprint-sensitive sites. UV cure requires less equipment on site. No boilers, no water tankers, no steam generators. For rehabilitation in residential areas, hospital grounds, or city centres, that is a practical advantage.
Carbon-reduction requirements. UV curing uses less energy and produces fewer emissions than thermal methods. For engineers and contractors working within sustainability-weighted evaluations, that is measurable.
Every iPlus Glass UV liner is manufactured under ISO 9001:2015 certification with 28 quality control checks completed before dispatch. For engineers looking at what to consider before specifying trenchless rehabilitation, that manufacturing rigour is part of the specification confidence.
Choosing the Right Cure Method
UV pipe lining gives specifying engineers a cure method that is faster, lighter on site, and better suited to flow-sensitive and time-constrained projects. iPlus Glass UV is the liner system we manufacture for exactly those conditions, backed by over 50 years of CIPP engineering.
Explore iPlus Glass UV for full product specifications, or get in touch with our technical team to discuss your next rehabilitation project.
