by Margie Church, editor
Cured-in-Place Pipe (CIPP) is a means to rehabilitate deteriorated pipelines without digging them up. Sanitary sewer and storm waterlines are the biggest application of the process, but it can be considered to remedy other types of pipelines, including pressure lines.
CIPP was invented in the United Kingdom by Eric Wood. With financial backing from Brian Chandler and Douglas Chick, Wood formed Insituform Group Limited and began installing CIPP in the United Kingdom in 1971.
Today, Insituform is a vastly different company than the original business founded more than 35 years ago. Until 1992, Insituform was primarily in the business of licensing proprietary trenchless technologies to other companies throughout the world. When Insituform acquired its licensor in 1992, its name changed to Insituform Technologies, Inc. As a result of successive licensee acquisitions, Insituform’s business model evolved from licensing technology and manufacturing materials to performing the entire Insituform CIPP process and other trenchless technologies in the potable water and industrial markets. Insituform now has operations throughout North America, South America, Asia, Australia, and Europe.
Lynn Osborn joined Insituform North America as an engineer in 1984, and he knows firsthand the challenges of gaining market understanding and acceptance for CIPP. Today, Osborn is Insituform’s Senior Applications Manager. “Back then, there were licensees all over the U.S. Research and development, technical marketing, sales support, and quality control were all wrapped up in engineering. Those were exciting times,” Osborn said. “There was also no direct competition. That may sound like a wonderful spot to be in, but people were hesitant to accept CIPP, and we had our work cut out for us.”
Municipalities are the biggest consumers of CIPP. “We have tremendous respect for our municipal customers, however, as buyers, they are not typically comfortable in the innovator and risk-taker roles,” said Dee Bryant, Insituform Director of North American Sales. “They also have fiduciary responsibilities. You have to start with small projects and find your successes slowly.”
That time-consuming, slow process presents itself as a barrier to market entry for many companies. There are significant up-front costs, and the return on investment takes years. It’s also a big reason why Insituform invests untold numbers of hours and dollars on customer and industry education.
Tutorial on the processes
CIPP is only one of three basic processes used to remediate gravity lines. (Renewing potable waterlines is a trenchless application that is discussed separately. See the Waterline Remediation article on page 18 for more information.) There are degrees of trenchlessness and deciding whether a trenchless remedy is suitable, as opposed to “dig and replace,” is done on a case-by-case basis.
Pipe bursting is a potential solution when the pipe is deteriorated and a higher capacity line is also desired. First, access points are dug along the existing line. Then a jackhammer is used to vibrate and burst the pipe at the same time a slightly larger polyethylene pipe is pulled through the space. The old pipe falls into the surrounding soil, and the new pipe is left in its place.
Fold and Form
Fold and Form is a truly trenchless technique to consider when line capacity and infiltration from lateral service connections are not concerns. Fold and Form is a slip lining technique that involves pulling a PVC pipe that is pre-configured and pre-cured into the deteriorated line. The original line’s capacity is reduced somewhat using Fold and Form.
CIPP is the premier trenchless technique. If a line has many lateral service connections, then CIPP is the gold standard. CIPP is a very fast solution compared to “dig and replace,” which can cause social impacts, such as service disconnections, the rerouting of traffic, and loss of business revenue during remediation.
CIPP also is a “green” process. This no-dig solution protects the environment from destruction at the street level and from the debris that surface when lines are dug and hauled away.
In addition, the design life of the cured pipe is generally 100 years, making its amortized costs lower than any other kind of pipe remediation used in today’s market.
The first step in the CIPP process is to clean the line. A closed-circuit television (CCTV) camera equipped with a high pressure water jet is sent through the pipe to remove debris. Next, a robot is sent through to videotape the pipe and mark all the service connections. This video is critical to help decide how to approach the repairs and to re-establish the service connections when repairs are complete.
During the process, a thermoset resin-impregnated felt tube is either inverted or pulled from one manhole to another and cured using hot water or steam. After the cure is complete, a robot is sent through the pipe to reopen the service connections and collect a post-video, which is used as a quality-control check. The cured pipe will withstand the chemical environment, soil loads, and groundwater loads. Often the line’s flow capacity increases following rehabilitation because of the smooth, joint-less interior of the finished CIPP product.
Insituform’s highly-engineered CIPP tubes
Insituform began manufacturing its CIPP tubes at its Memphis, Tennessee, plant in 1981. In 1988, in a move to become more integrated, it started manufacturing its own felt and tubes at its Batesville, Mississippi, facility. The tubes are highly engineered to stretch circumferentially and longitudinally, and withstand the pressure they experience during installation.
The polyester fibers arrive in various deniers (degrees of fineness) and look like bales of cotton. First, the fibers are needle-punched to create rolls of nonwoven felt. Some of the felt is coated with a thermoplastic material to form an impermeable outer layer. The felt material, both plain and coated, is then slit to the proper width and sewn into tubes and are ready for resin impregnation.
“We are always looking for methods and products that work better at an equal or lesser cost,” Osborn said. “There is a tremendous commitment to research here.”
Insituform designed it next-generation iPlus Infusion® tubes for pipelines 6 to 12 inches in diameter and up to 750 feet in length. Insituform manufactures the iPlus Infusion tubes, and then the installation crew brings them to the jobsite. A robust pull-in method is used to install them in the host pipe. iPlus Infusion tubes are cured with low pressure steam, which reduces energy and water consumption, and virtually eliminates discharge of the process water into the sewer system.
For pipes 30 inches to 96 inches in diameter, Insituform designed the new iPlus Composite® tube. This tube has two reinforcing layers of either fiberglass or carbon to provide higher strength and stiffness (flexural modulus). Because the tube is thinner, it requires less resin and it is lighter. More of these tubes can be brought to the jobsite per truckload, reducing transportation and labor costs, time, and materials.
Insituform formed a separate division, Mississippi Textiles Corporation (MTC), to sell its tubes to other CIPP providers.
Chameleon resins for CIPP
The demands placed on CIPP resins are pretty complex. From Insituform’s perspective, the only way to help ensure the best results was to standardize its resin specifications, which it did in 1995.
“We put high demands on our resin manufacturers and their products,” Osborn said. “Everything from handling characteristics to pot life to physical characteristics has to be considered. Premature exotherm will ruin a job and cost thousands of dollars. That’s just one example. Our resin suppliers worked hard with us to formulate the right products for us,” he said.
Filled and unfilled (neat) isophthalic resins and unfilled vinyl ester resins are used for CIPP. Osborn said filled isophthalics are used for municipal installations. Isophthalic resins provide the right corrosion resistance against sulfuric acid (the corrosive agent formed in sanitary sewer lines), and the filled versions provide higher flexural modulus (stiffness) without detracting from the physical performance of the finished composite.
Vinyl esters are only used in their unfilled form. In industrial applications where more aggressive chemicals, higher service temperatures, and higher concentrations of chemicals are found, a vinyl ester is a better weapon. They have higher heat, physical, and corrosion resistance capabilities, to survive and thrive in those applications. Vinyl ester resins also are used in low pressure CIPP applications.
Controlling its destiny
As competition entered the market, Insituform began acquiring its licensees and expanding its manufacturing capabilities to make it a completely vertically integrated company. Insituform’s goal was always to provide the best products and services by controlling all the variables in the process. Comprehensive training for employees also helps keep quality high. Insituform provides in-house training by its own staff and offers more than 40 e-learning modules for many job descriptions. “We encourage individuals to make training a personal responsibility to maintain their professionalism and skill level,” Bryant said.
The company also instituted customer satisfaction programs as another quality-control method. Customer evaluations query everything from timeliness and safety to final job results. “If there’s a hiccup, we want to know about it, address it, and determine whether we need to evaluate training to help ensure the problem doesn’t occur again,” Bryant said.
Insituform is the only company to make a commitment to the market on national and international levels, with staff all over the world. “We bring high brand standards and professionalism wherever we are,” Bryant said. “We have business developers and offices in most large metro areas worldwide and more than 1,600 employees worldwide.” Europe remains a cornerstone market, while Asia, India, and Australia are growing opportunities.
Insituform’s persistence and ingenuity have paid off. Insituform can say it put “trenchless” on the map. The company’s experience, international market commitment, and untiring search for the next innovation in trenchless technology have made the name Insituform synonymous with CIPP.