When underground pipe infrastructures began, many municipalities and businesses turned to cast iron to transport water and waste. While cast iron is a durable material, over time corrosive materials eat away at the walls and cause the pipeline to break. Water, waste or caustic chemicals can leach into the surrounding soil. Finding a way to repair the plumbing while not disturbing the soil, potentially spreading hazardous material, is a task workers must face. Cured-in-place pipe offers corrosion resistant composite protection without the traditional installation methods.
Read: Why CIPP Is Growing Rapidly for Drinking Water Mains
Municipal Corrosion Problems
In most municipalities, corrosion issues occur over time with the continual flow of water or wastewater through a cast iron or copper pipe. While these pipes are designed to last for decades, the constant use wears them down, sometimes before their time.
When dealing with water pipes, there are many different reasons the lines may show signs of corrosion. Unbalanced pH levels, either too high or too low, are a standard issue. Other issues may include temperature, air in the lines, chemical makeup or other infiltrates like sand or sediment.
For copper water lines, tell-tale signs include a blue tinge to the pipeline itself. Laundry washed in water from the corroded line may also have a blue tint to it. Blondes washing their hair in contaminated water may also find their strands turning blue.
For cast iron lines, such as the ones that may run from the municipal water supply up to the home, rusty water is the first indication. The rust may stain clothes and may contain contaminants that could prove harmful to your health should you ingest any.
If water has been contaminated, a corroded pipe could cause trouble for the surrounding soil if hazardous materials leak into the ground.
Cured-in-Place Pipe (CIPP)
Cured-in-place pipe (CIPP), is a trenchless solution to pipeline repair. (Trenchless solutions are discussed in the article Evaluating Trenchless Technology for Water Infrastructure Life Extension.) This repair method began in the 1970s when Eric Wood needed to repair a broken pipe that ran beneath his garage floor. Instead of breaking up the concrete and removing then replacing the pipeline, he ran a liner through the existing tubing. With minimal disruption to the ground surface, it is a faster and often more economical way to complete repairs.
As the name implies, CIPP is a line within a line. The benefit being that current lines are not removed, so they offer added stability and protection for the new pipe. In its uncured state, the liner is flexible and is either pushed or pulled through the pipeline. Once in place, workers inflate the line so that it fits snugly against the current piping. This inflation mitigates the need for grouting between the new and old lines.
CIPP has a lifespan of 50 years. However, the overall lifespan will depend on the soil, the water pressure load and the corrosive nature of the transported substance. The lifespan also depends on the state of deterioration of the existing pipe. Liners in fully deteriorated plumbing have a lifespan of only 50 years. Cured-in-place pipe used in partially decayed lines may last slightly longer.
Read: Common Causes for CIPP
CIPP Resin Types
While all CIPP uses resin, there are different types depending on the end use. Although water and waste pipelines do not need a resin composite that is highly corrosion resistant, industrial plants do. Typically, one of three types of resin permeates the flexible liner: epoxy, polyester or vinyl.
Epoxy Resin Liners
Of the three types, epoxy resin is the most expensive. However, unlike the other models, this resin does not shrink during curing and does not release dangerous fumes. As such, it is the first choice of contractors needing to line indoor plumbing lines. Epoxy is applicable for residential, commercial and industrial usage.
While epoxy resin cures rather quickly, it cannot be pre-saturated into the lining. Workers must soak the liner on site and immediately insert it laterally into the pipe. Because of the short curing time, the line is quickly returned to active service after installation.
Polyester Resin Liners
When compared to epoxy and vinyl, polyester resin is the most commonly used. This affordable liner is presoaked and shipped to the site. It works well in storm and sewer lines, and city projects often use these liners. Due to the resin mixture, its cure time can vary from a few minutes to several weeks. However, municipalities only order the longer cure time if they are ordering from a contractor that is not located nearby.
Unlike epoxy, polyester is best used in outdoor settings because the liner gives off a strong odor. It also tends to shrink slightly as it cures. However, proper calculation before installation mitigates that problem.
Vinyl Resin Liners
The final option is a hybrid of epoxy and polyester known as vinyl resin. It tends to be costlier than polyester and has some of the same shrinkage and odor issues. However, it is exceptionally resistant to corrosive environments.
Vinyl resin liners do have health concerns associated with its use. Many of these corrosion-resistant composites can emit volatile organic compounds (VOCs) into the surrounding soil. Because of these concerns, companies may employ newer vinyl mixtures known as no-VOC vinyl ester resins. They still offer the same extreme resistance in a corrosive environment, but do not leak organic compounds into the soil.
CIPP Treats Damage Quickly and Efficiently
Corrosion happens in water, waste and industrial usage lines. Using a corrosion resistant CIPP liner to repair the damage allows workers to repair the damage quickly, typically within a week or less. CIPP liners provide long life and better resistance than some traditional composites.