Tips for Choosing the Right CIPP Liner

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Choosing the right lining material for a cured-in-place pipe (CIPP) rehabilitation project can never be an “off the shelf” decision.

Research and development in the world of CIPP liners has resulted in a wide spectrum of new solutions, all created to meet unique requirements and address the proven acceptance of CIPP as a viable way to extend the life of a pipe without digging or causing significant disruption to communities.

Traditional felt lining materials, first introduced in the 1970s, have been used successfully around the world for the rehabilitation of sewer pipes. The proven, decades-long history of extending the life of gravity sewer lines using quality felt CIPP liners has justified the continued evolution of this important product to go beyond mainlines. One of the most significant advancements has been the development of a variety of CIPP felt liner solutions for relining lateral pipes, as well.

RELATED: CIPP Market: Nearly 50 and as Strong as Ever

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applied felts

Preparing for the shipment of custom-made Applied Felts CIPP liners.

The real key to felt liner evolution, however, has come directly from the CIPP installers in the field to meet their needs. Developing liners that perform well for contractors and deliver long-lasting results for system owners is always a goal. Advancements such as flame-bonded, PU-coated felt liners, for example, allow for more extreme environmental and procedure requirements while providing greater flexibility in the field.

With the high acceptance and success rates of CIPP solutions for gravity sewer lines, lining manufacturers have evolved product offerings through the development of additional liner innovations — including reinforcement of felt products with fiberglass — for added strength in gravity, pressure pipe and potable water systems.

By combining fiberglass reinforcement with traditional felt liner material, the unique properties of each are blended and fully integrated to provide the strongest, most robust liners available. Most fiberglass-reinforced products, if manufactured properly, will perform and install just like non-reinforced liners; they use the same procedures, equipment and operations.

The benefits of fiberglass-reinforced liners include a matrix that reduces the thickness of liners, delivering significant resin savings and, therefore, overall lower material costs. These liners typically weigh less, making transportation, handling and installation faster and easier. Well-manufactured glass-reinforced liners should stretch up to 10 percent to the existing pipe wall, ensuring a close fit with faster impregnation rates and reduced installation times. Providing excellent chemical resistance against sewer effluent elements, fiberglass-reinforced liners also provide superior physical and mechanical properties upon ASTM testing.

RELATED: Relining on a Grand Scale

Even though these new, dynamic technologies, among others, provide a wide array of choices, since rehabilitation projects are so diverse, each job must be evaluated individually before deciding which lining solution will best suit a particular project. Every step of the way it is critical to work hand-in-hand with the liner manufacturer to ensure the delivery of a custom solution that will stand the test of time.

Step 1: What are the unique characteristics of the job?

Before selecting a liner, several variables must be considered, including geographic location, time of year (e.g. outside temperature) and so much more. Call on liner manufacturers who will deliver custom solutions to work in partnership with you to determine which product — or combination of products — will best suit your unique installation.

Step 2: Which system is being used to install the liner?

Not all CIPP installation systems are the same. A contractor or a system owner who is self-performing the work must take into consideration things such as availability and location of a wet-out facility and capabilities of the installation equipment used. The comprehensive system must also include quality resin and other materials, which are equally important to evaluate prior to selection.

Step 3: Are the raw materials used in the manufacturer of the liner top-of-the-line?

Like anything else, a liner is only as good as the raw materials used to create the finished product. The best liners will be those manufactured by a company that has full control of the process, from the purchase of raw materials to the technical support in the field. It’s important that the raw materials, including polyester fibers, polyurethane granules, fiberglass and other materials, are inspected and thoroughly tested before they are used in the manufacture of the final product.

Step 4: Know your options.

It is critical to know the many options available to you for the manufacture of your finished liner. Based on your unique needs, steps and materials used in the manufacturing process can be varied. For example, choosing the right polymer coating, which is crucial for the resin system as well as installation and curing methods, must be part of the equation. Another decision is the selection of the method in which the liner is closed. Flame-bonded or sewn are two popular options, and new technologies also provide for a high frequency welded overlap seam for use in open-end (or blind shot) liners as well as pull-in-place applications. Once pressurized inside the liner, the flexible tube presses the liner against the host pipe during the curing process.

Step 5: Does the liner manufacturer have a quality QA/QC program?

During the manufacturing process it is imperative that liners are stress-tested every step of the way. Characteristics such as density, thickness, fiber distribution/evenness, strength and weld-ability should all be continually evaluated. The manufacturer should also assure that no pinholes are present by monitoring coating uniformity, mass and weight distribution. Liners should be destructively tested for density at various pressures, tensile strength, coating distribution and more. Samples of the final product should be taken and tested once again for accuracy in circumference, density, length, coating integrity, weld strengths, and other properties that you specify.

applied felts

Known globally for mainline CIPP solutions, Applied Felts has developed a suite of innovative products for lateral relining applications.

Step 6: Does the liner manufacturer stand behind its product?

One of the most important things in the purchase of lining materials is direct and ongoing support from the liner manufacturer. Everything from determining the best raw materials, managing the manufacturing of the product, coordinating timely delivery, training your team and standing by to help you – day or night.

RELATED: Tips for a Successful Rehab Installation

Ultimately the goal is to rehabilitate pipes using CIPP to minimize disruption, cost and time while maximizing the life of the pipe. Purchasing lining materials is a huge responsibility, and one you should not take lightly. The best tip in choosing a CIPP liner? Find a manufacturer that meets the above criteria. Inquire about their R&D initiatives to address your future needs and consider a visit to their manufacturing facility to learn first-hand the intricacies involved in producing quality liners.

Using the best liner is not a simple buying process; it is strong collaboration and sharing of knowledge that requires ongoing partnership between you and the manufacturer to install the best product possible.

David Blades is operations director and Mark Chandler is technical manager at Applied Felts.

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