Spiral Wound Lining: A Sustainable and Trenchless Pipe Rehabilitation Method

Modern trenchless technology has been in the works since 1970. Since then, we have utilized innovative methods, such as horizontal directional drilling, horizontal auger boring, cured in place pipe lining, and pipe bursting, to repair, maintain, and replace pipelines. Another method in this trenchless technology revolution is spiral wound pipe lining, which first appeared in the 1980s

Like other trenchless methods still in their infancy, some entities and contractors hesitate about using spiral wound lining. However, this unique pipe rehabilitation method causes minimal surface disturbance compared to other trenchless technologies.

How Does Spiral Wound Pipe Lining Work?

The spiral wound lining method involves building a new pipe within an existing pipe. It doesso by feeding a continuous eight- to 12-inch-wide strip of polyvinyl chloride (PVC) or high-density polyethylene (HDPE), from above ground through an existing access point and then winding it into the pipe. As the thin strip winds into the existing pipe, the material joins together, molding to the original pipe’s shape. After the new lining is in place, cementitious grout is installed in the annular space between the existing pipe and the new lining. The method of joining the continuous spiral joint can be done in three ways—tongue and groove joint by hand, tongue and groove joint by machine, or fusion joint by machine.

Machine Vs. Manual Spiral Wound Lining

Both machine and manual methods utilize plastic with a ribbed profile design to rehabilitate culverts, storm drains, and sewer pipes, but there are key differences to note. The machine-wound process uses spools to unwind the plastic strip and feed it into hydraulically-powered stationary machines or traversing machines within or at the pipe’s entrance. The machines continuously wind the material into the host pipe and mechanically lock or fuse the joints together. This method creates joints that are watertight and impervious to root intrusion.

Manually-wound liners are best suited for large pipe installations. This method is usually used for 36-inch diameter pipes and above since the space needs to be large enough for a person to enter the pipe. The PVC comes in coils or panels that workers can lower into the pipe. Workers then join the edges of the material together incorporating male and female double locking edges as they move their way down the length of the pipe, creating a water-tight seal. Any space left between the material and the host pipe is then filled with cementitious grout.

The Challenges of Spiral Wound Lining

This method requires extensive quality control. In the case of the fusion joints by machine wound lining method, workers need proper training to ensure the material is properly fusion welded at optimal temperatures. If not done correctly, the joints could fail at any moment, and no one would notice until it is too late.

The spiral wound lining method is also not ideal for sharp bends or long stretches of pipe rehabilitation. Since the equipment for this method is driven by hydraulics, it does not have the power to maintain the speed of installation or stability of the new pipe beyond about 1,500 feet.

When using the spiral wound lining method, engineers and entities must account for the new pipe’s smaller interior diameter. This is because the empty space between the old pipe and the new pipe will be filled with cementitious grout, which will decrease the pipe’s diameter. Although it may seem small, this may reduce the rehabilitated pipe’s carrying capacity. In some cases, the hydraulic capacity is maintained or improved because the new lining is significantly smoother than the host pipe.

Overall, spiral wound lining is beginning to pick up steam in the US,it as a sustainable alternative to other invasive pipe restoration construction methods. States taking interest in this method are drawn in by the minimal excavation and the absence of air quality concerns that result with other rehabilitation methods due to chemicals released during the curing process.