The SPR™EX Expansion Process

Explaining how SPR™EX Expands

We receive many questions on how SPR™EX expansion works, so the following is an explanation of the process. SPR™EX is an innovative lining solution for gravity pipelines from 6” – 42” diameter. SPR™EX is a tight-fit liner and upon installation, the PVC liner is expanded directly against the host pipe wall, requiring no annular space grouting.

SPR™EX expansion process for a tight fit installation
SPR™EX Expanding

SPR™EX is a mechanical installation process. The equipment consists of a drive tray assembly and a winding cage that is sized smaller than the host pipe. This is done in order to navigate host pipe anomalies such as offsets, ovality and other pipe defects. The installation equipment is lowered in the manhole or access chamber and will remain stationary during the installation process. The operator will then begin to feed profile into the winding assembly. The liner is constructed by the continuous interlocking of subsequent wraps of profile. The operation continues until the liner reaches the termination manhole or access chamber then is torsionally restrained.

Typically, SPR™EX liners are installed from the downstream to the upstream structure then expanded with the direction of the flow. To understand the expansion process, we must explain the SPR™EX double-locking mechanism that creates a continuous liner from a PVC strip.

SPR™EX Double-Locking Mechanism

The SPR™EX profile contains a primary and secondary lock. The primary lock is sealed by a lubricant that is simultaneously pumped into the female or primary lock while the liner is being constructed. In between these two locks is a cutting wire, designed to hold the liner at a fixed diameter until the operator initiates the expansion process.  

Pulling the Cutting Wire

Expansion of the liner begins by pulling the cutting wire, severing the secondary (sacrificial) lock. While the cutting wire is being progressively retracted, the winding machine continues to wind more profile.  The lubricating sealant in the primary lock allows adjacent profile wraps to slide relative to one another as more profile is wound into the pipeline.

The SPR™EX Expansion Process
SPR™EX Expanding for a Tight-Fit

As the liner expands in diameter, it fits tightly against the inside wall of the deteriorated pipe, and this process continues progressively down the pipeline.

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