Is a CIPP Liner The Right Fit for Your Trenchless Rehabilitation Project?
While CIPP is a useful procedure and works to correct most minor leakage problems, it isn't right for every project.
Your lawn is green and luscious. From all outward appearances, it looks as though it is well fertilized and well kept. Until you step foot on it and realize that it is soggy and squishy even though it hasn’t rained enough to make it that way.
The bad news is there is either a sewer or water line leak in your yard.
The good news is the plumber may not have to dig up the entire yard to fix it if you can use a CIPP liner instead of replacing the pipe.
What is a Cured-in-Place Pipe Liner?
Cured-in-place pipe (CIPP) is a fabric liner impregnated with resin. Contractors use the liner to repair leaking pipes as an alternative to digging up the line and replacing the entire pipeline. As this method doesn't require exposure of the whole pipeline, it's considered trenchless rehabilitation. (Read Trenchless Rehabilitation Evaluation: How to Properly Inspect and Locate Damaged Pipelines.)
To install a CIPP liner, the contractor may dig an access hole better known as an entry point. If possible, the contractor may access the line from an already uncovered section through a utility hole or similar access point.
The liner is then pulled into place with an apparatus or inverted and pushed through the line. They then expand the liner with warm air which also helps to cure the resin, hardening it. In some cases, the resin requires a UV light source.
Once complete, the liner acts as a new pipe with the original line serving as a stabilization unit. While CIPP is a useful procedure, it isn't necessarily right for every project.
What is a CIPP Liner Predominantly Used For?
CIPP is one of the more popular methods of trenchless rehabilitation. There is little to no disruption of your yard. It also often takes less time to complete the repairs than traditional trenching methods. What types of projects can successfully use CIPP as an option?
Tree Root Infiltration
If a pipeline has even the smallest crack, roots can work their way into the structure. Once roots infiltrate the line, they can cause further damage and block the flow of water and sewage.
Using a CIPP liner keeps the roots from interfering with the flow without having to replace the original plumbing. (Read The Harmful Effects of Tree Root Infiltration on Potable Water Piping.)
While root infiltration is a common cause of broken pipes, it is not the sole reason. Temperature, soil conditions, and pipeline age can attribute to the overall degradation of the pipeline. As long as the pipe is not missing large sections, you can use a CIPP liner to rehabilitate the problem line.
Degraded Sewer Lines
Overtime sewer lines fall apart. Most sewer lines have a lifetime of 50-75 years. As the lines begin to decline, contaminants can get into stormwater, which can impact the overall water quality.
Many communities use CIPP to keep these contaminants out of the line.
Types of Projects Is a CIPP Liner Not Ideal?
While CIPP is an excellent choice for many line rehabilitation projects, it doesn’t work in every instance. In those cases, you will need to choose a different rehabilitation option.
The CIPP liner is not designed for all over coverage. Instead, it is best used for partial coverage of lines that may be broken or degrading due to age. You cannot line fitting tees and connection points. You may have to replace any misaligned connectors or fitting tees, or you may need to leave a gap between the lining and the fitting.
Broken System Components
During a system repiping, there may be no-hub coupling straps on a drain or vent that failed. Often it is due to corrosion in the system, but may also be due to a structure not being up to code. No matter the reason, you cannot line a pipe like this as it has an increased risk of failure without the straps in place.
Other examples of broken system components may include corroded vent lines which cause large sections of pipe to be missing. Without the support of the original pipe, the CIPP liner will fail.
However, these issues are often overlooked due to the difficulty in locating the exact area of failure.
Pipe Grade Issues
Pipe grading malformation can cause issues and decrease the overall structural integrity. However, lining the pipeline with a CIPP liner will not correct the defect. You need to replace the pipe to fix the grade issues.
Is a CIPP Liner Right for Your Trenchless Projects?
CIPP works for many different types of pipeline issues. However, it just isn’t the best option. For example, if the lines are severely deteriorated, you shouldn’t try to use a CIPP liner. While the resin does harden, it needs support from the original line to be successful.
If the project is subjected to exterior corrosion, then CIPP liners are not the appropriate choice. Exterior corrosion will eat away at the pipe, causing structural instability. If there is no protection in place, once the liner is in, corrosion continues to degrade the pipe, fittings, and tees to the point of collapse. (Read How to Detect and Control Hydrogen Sulfide Corrosion Problems in Sewer Pipes.)
Smaller diameter pipes, with an interior diameter of 4-6 inches, are not ideal for CIPP liners. The tight space makes it challenging to pull the liner through. The limited dimensions also make it difficult to inflate the liner so it can harden adequately.
As CIPP reduces the usable diameter of a pipe slightly, this further constricts an already small tube to the point of making it difficult to use after the completed repair.
However, larger diameter pipes that are not severely deteriorated can benefit from the use of CIPP liners instead of other rehabilitation methods. With the larger diameter, you have plenty of room to pull the resin impregnated fiber into place. There is ample room put push air through inflating the liner and helping to harden it at the same time.
Pipes with bends can benefit from the use of CIPP liners. As the fabric is flexible, before curing, the liner easily bends to the shape of the original pipe. Other lining methods require multiple pieces and only work on straight sections.
Once cured, the CIPP line becomes one solid line without connection points which may leak later.
Alternatives to CIPP
Sadly, CIPP doesn’t work for all pipeline repairs. In this event, you should speak with your plumbing specialist to determine available courses of action. One technique which may be beneficial is pipe bursting.
With this trenchless method, a bursting head breaks up the original pipe. Attached behind the head is a new line that follows into the space the old plumbing existed. There is more to pipe bursting, and it does require a more massive entrance and exit trench that CIPP.
However, it is still a viable trenchless solution that is less damaging to your property that traditional trenching replacements.
A CIPP liner is an excellent choice when rehabilitating water and sewage lines. While this method isn’t feasible in all cases, it works to repair many common issues homeowners encounter. Always speak with a plumbing service professional about your options before committing to any project.
Written by Denise Sullivan | Technical Writer @ Trenchlesspedia
Denise Sullivan is an accomplished freelance writer from Louisiana, with a Associate's Degree in Journalism from Eastern Oklahoma State College. She also graduated from East Central University with a Bachelor's in Biology. Denise began her writing career writing operations and maintenance manuals and software utility manuals for flight simulators. Since, she has expanded her writing to a broad spectrum of topics.