Trenchless Pipe Rehabilitation Using the CIPP and Patch Liner Methods

If a leak is detected during a pipe tightness test, CIPP (Cured-in-Place Pipe) and patch liner systems offer a quick and cost-effective solution. The primary advantage of these techniques is that the pipe can be sealed without the need to excavate the affected sections. However, do not underestimate the expertise required — both methods should only be carried out by experienced professionals and are not suitable for DIY enthusiasts!

Two Methods, Many Advantages

It’s clear that both the CIPP and patch liner methods offer substantial advantages. There’s no need to close roads, less dirt and noise is generated, and the overall effort and cost are significantly reduced. This is not just appreciated by the client but also by the neighbours. Another major benefit: the durability of these trenchless methods extends for several decades. These are by no means temporary fixes, but rather high-quality, sustainable rehabilitation solutions. But what exactly is the key difference between these two techniques?

Patch Liner Rehabilitation with the Inflatable Packer

The patch liner method is a proven technique for repairing smaller damages, using an inflatable packer. These devices come in various lengths and shapes, such as bendy packers. Together with specialized materials like resin, laminate, and foil, shorter pipe sections can be effectively repaired. This method is suitable for sealing faulty welds, cracks, root damage, or corrosion-related leaks. Even though these flexible packers appear durable and robust, careful handling is essential. This ensures not only your own safety but also allows for the reuse of the packer multiple times. Therefore, any stones, sand, or sharp objects inside the pipe, along with deposits and encrustations, must be removed prior to the repair to prevent damage to the packer. Following the process, it’s recommended to inspect the repair using a pipe inspection camera.

Inflatable house connection packer for small diameter pipes

Safety First

The packer itself, the hoses, and all other accessories must be checked for completeness, damage, and durability (this includes the resin) before each use. When starting the operation, ensure the use of full protective clothing, the correct working pressure, and watch out for people in the danger zone! Detailed instructions can be found in the operating manual for your equipment, which even professionals should regularly review. Using a push bar with air passage, the packer wrapped with resin-soaked laminate is pushed to the leak and inflated with compressed air at the targeted location. The sticky fibreglass adheres to the pipe wall and cures quickly. For example, Carbolith components cure within 50 to 90 minutes.

Accessories for patch liner rehabilitation. Pictured are a thin laminate mat, rehabilitation resin, hardener, and special push rods.

Once the material has fully hardened, the packer is deflated and removed. The dried "shell" remains in the pipe, ensuring it is fully functional and load-bearing again. After completing the repair, it is essential to clean the working materials carefully yet thoroughly. During this process, keep an eye out for any damage to the inflatable packer. In case of doubt, consult your specialised supplier, who will gladly offer advice and assistance.

Trenchless Pipe Rehabilitation over long distances

Unlike the patch liner method, the CIPP method (also known as slip lining) is not used for repairing specific points but rather for significantly longer sections. It can even be employed for the complete rehabilitation of an entire pipe or sewer system. The concept is similar to the patch liner method, as the liner method also creates a “pipe within a pipe” using resin and specialised fabric materials. Again, this process is minimally invasive, meaning the entire section does not need to be excavated or replaced.

Trenchless pipe rehabilitation works without tearing, excavating, replacing, filling or asphalting.

Comprehensive renovation using the CIPP procedure

Instead of using a wrapped packer, the liner method involves inserting a long fabric tube into the pipe. Once positioned, the resin-soaked interior of the liner is pressed against the pipe wall with pressure, lining it from the inside. The flexible material adapts perfectly not only to the pipe’s layout but also to different pipe diameters. One fascinating aspect of the liner method is the use of a continuous liner, which can rehabilitate very long sections. During the curing process, auxiliary methods such as hot water, steam, or UV light may be used. The curing time typically takes several hours. Just like with the patch liner system, pipes rehabilitated using the slip liner method can be quickly put back into operation.

Author: Elisabeth Pietraß
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