When it comes to trenchless pipe rehabilitation, the curing method you choose affects speed, quality, and overall job cost. Light-cured systems, whether traditional UV or newer LED-based, have become increasingly popular because they eliminate the need for hot water or steam. But not every UV curing system is the same.
The wavelength behind the light source plays a bigger role than most people think. It affects how quickly the resin cures, how well the light travels through the liner, and which resin systems it can work with.
So, what wavelengths do these systems actually use, and why do they matter? Let’s take a closer look.
Traditional UV Curing Systems: Broad-Spectrum, 315–400 nm
Traditional UV curing systems have been around in pipe rehabilitation for decades. Most use mercury vapor or metal halide lamps. These lamps produce a wide range of ultraviolet light. For curing liners, the most useful range is usually the UVA band, around 315 to 400 nanometers.
That is the range where the resin starts reacting and begins to cure. The photoinitiators inside the resin absorb the UV energy. They then react and start the hardening process. This process turns the liner into a solid structure.
The good thing about broad-spectrum lamps is that they can work with more than one resin setup. That flexibility is why a lot of crews still use them.
The downside is the heat and power demand. These lamps can run hot and use more energy. Crews usually need extra cooling during the job. The equipment can also be bulky. That can make installations more challenging in smaller pipes, tight bends, or complex layouts.
Still, traditional UV systems have their place. Crews commonly use them on larger mainline GFRP liner jobs. These jobs often need stronger light output and more curing time because of the pipe size and liner thickness.
UV LED Curing Systems: Targeted Wavelengths, 315–405 nm
UV LED curing is more focused than traditional lamp curing. Instead of sending out a wide mix of wavelengths, LED systems use a narrow band of light. That light matches the resin chemistry.
The most commonly used peak wavelengths in pipe lining LED systems fall in the range of 365 nm and 385 nm. Some systems operate up to 405 nm, depending on the resin formulation.
That focused output is what makes LED systems different. Because the light matches the resin, less energy is wasted as heat. This makes the curing process more efficient.
LED cure heads are also usually more compact than older lamp packs. That can help when crews work through bends, transitions, or smaller pipe sizes.
Some systems use more than one wavelength, like 365 nm and 385 nm together. This can support better cure depth in certain liner materials.
Glass fiber liners also work well with UV LED curing because fiberglass is nearly transparent to UV radiation. That helps create a more consistent cure. It can also improve pull-through speed when the job setup allows it.
UV Curing System Options: Blue LED Systems, 444–457 nm
A third category worth understanding is blue LED curing. This system operates outside the UV spectrum and into the visible light range.
Blue light curing systems emit at a specific and narrow band, typically 444 to 457 nanometers. This range falls in the blue portion of the visible spectrum rather than in the ultraviolet range.
The key advantage of this wavelength range is penetration depth and intensity. Blue light systems provide deep and consistent curing when paired with compatible resin systems. Incomplete curing at the interface between the liner and host pipe is one common cause of liner failure. That is why proper cure depth supports a more structurally sound repair.
Blue light systems also require specially formulated resins. These resins only react to light in the 444–457 nm range. At first glance, this sounds like a limitation. In practice, it can be a major operational benefit.
The resin won’t begin curing until it’s exposed to blue light. As a result, installers have a longer working window between liner saturation and inversion . There is less race against the clock.
This reduces stress on crews and helps lower the risk of the liner beginning to cure too early. Once the LED head is pulled through, the cure happens quickly and with strong control.
The trade-off is that blue light systems are currently better suited to laterals and smaller drain pipes, typically 2 to 18 inches in diameter. They are not usually the first choice for large-diameter mainline applications.
The resin specificity also means contractors need compatible liner materials. However, manufacturers continue to expand the range of compatible products as the technology matures.
Knowing how these wavelength ranges work makes it easier to choose the right system for the job. The right UV curing system does not just affect curing speed. It also influences installation quality, efficiency, and long-term liner performance.
For contractors exploring additional rehabilitation options, IPP Solutions also offers SIPP spray lining technology. This alternative rehabilitation method restores pipes without using liners or UV curing.
Reach out to IPP Solutions to find the right UV curing system or rehabilitation technology for your next project.
