Top Secret! Odd-Shaped Pipe Lining Tricks Revealed

Learn how a unique pipe rehabilitation system is a no-nonsense solution for non-circular pipe lining.
Top Secret! Odd-Shaped Pipe Lining Tricks Revealed
The spiral-wound liner system can be used to line even pipes with non-conventional shapes.

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Spiral-wound pipe rehabilitation offers trenchless repair of sanitary sewer, combined sewer and stormwater lines without curing. 

Sekisui SPR Americas, LLC, headquartered in Atlanta, is currently the only company offering the machine-wound spiral technology. A single panel of either polyvinyl chloride (PVC) with interlocking edges, or extrusion-welded high-density polyethylene (HDPE), is reinforced by encapsulated steel. 

During repairs, the damaged section of the pipe is camera-inspected and cleaned. 

A hydraulic winding machine is then lowered into the manhole, and panel material is fed into the winder from an 8-foot-diameter spool on the surface. As material exits the winder, it forms a spiral, either by extruding along its own interlocking channel or by extrusion welding. 

The winder pushes the material spirally along the pipe’s interior surface until the liner reaches the next manhole, where it’s fixed into place, cut and sealed. Once the liner has been locked into place at both ends, temporary bracing can be erected if necessary as grout is injected into the space between the host pipe and liner. 

Circular pipe formation

A PVC liner is designed for sanitary sewer, combined sewer and stormwater lines from 6 to 30 inches in diameter. 

After a camera inspection in which lateral connections and branch lines are mapped, the line is cleaned and jetted. A wire mounted inside the liner retains the shape of the pipe until it reaches the next upstream access point. The product forms a circular liner in the shape of the pipe, but smaller, so that it moves freely to the next manhole or access point. 

At the access point, the end of the spiral is locked into place and the wire is removed to allow further expansion of the liner so it can fit tightly against the profile of the pipe, smoothing out jogs, offsets or imperfections. 

A lubricating sealant allows the liner to slide smoothly as it expands along its own interlocking channel. When the liner expands to its maximum diameter, it is cut and sealed at both ends. A robotic cutter reinstates lateral connections. 

PVC is used in pipes from 32 to 197 inches. It can be fitted to circular, custom or rectangular shapes and installed vertically in access shafts or wells. The hydraulic winder can either be fixed or moved along the profile of the pipe as liner is extruded. 

Odd-shaped pipe

For odd profiles, a customized hydraulic winding drive unit follows a predetermined shape. The winder bends the metal reinforcement inside the liner to permanently shape it to the host pipe profile. These liners require a bracing system to provide structural support during grouting. 

A pipe-grade HDPE material reinforced with encapsulated cold-rolled steel provides optimum rigidity and higher chemical resistance for lining sanitary sewer, combined sewer and stormwater lines from 30 to 120 inches. The profile of the liner is sealed using an extrusion welder to fuse the material. Because the welded liner itself provides the structure, a non-structural grout fills the annulus space. 

This article has been adapted from a previous Cleaner story


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