Cured in place pipelining (C.I.P.P. Corporation method)

Mainline Rehabilitation

Municipal Pipe Tool Co., LLC assembled the key ingredients and began C.I.P.P. Corporation installations in the Midwest with the assistance of Applied Felts, Interplastics, and Chemtron. This foundation for C.I.P.P. Corp. was a natural evolution for MPT after more than 30 years experience and sales of over $20 million in sewer work.

The materials for the C.I.P.P. Corp. lining process have been supplied to leading sewer lining contractors world wide by Applied Felts, Interplastics, and Chemtron for over 20 years. For more than twenty years the W E Rawson Group (Applied Felts) has been manufacturing felt products for the rehabilitation of pipes. It is one of the major suppliers of lining materials for the rehabilitation applications that are demanded by today´s installers. Demand has increased by over 50% per annum over the last 4 years. Hundreds of thousands of feet of liner have been installed in 21 countries. Over 60 construction companies use liners made by Applied Felts.

Applied Felts says:
"We can certify that our materials have been used extensively throughout the world in applications identical to those used by Municipal Pipe Tool Co., LLC and over a million linear feet have been successfully installed. We can certify that this combination of liner and isophthalic polyester resin is fully compatible and fully meets the requirements of ASTM F1216."

Applied Felts lining materials are made of polyester needle felt with one side of the tube coated with polyester polyurethane. A finished liner will typically be the result of exhaustive testing and quality control, currently those tests number 28. All liners are fully traceable through the manufacture of the original materials and all subsequent tests.

Applied Felts decided to use welded joints in the manufacture of its products used for inversion lining. Reasons are as follows::

1. The joints distort less than sewn joints when tensile forces are applied.
2. Tubes with welded joints of the coated felt will tolerate higher internal pressures before leaking of the coating occurs.
3. Welded joints provide better control of resin mobility during the critical curing phase of the liner.
4. Localized thickening in the joint areas resulting from the welding method ensure that when pressure testing of the finished product is carried out, failure does not occur in the joint area. This is often not the case with sewn joints.
5. All of Applied Felts liners are designed to take the maximum installation head specified by the customer. Every liner is tested to ensure compliance.
6. Generally, installation pressures are not restricted by the joint strengths when using Applied Felts materials. Specifically, the installation pressures are generally limited by a function of the maximum extension of the base fabric outside of the vicinity of the joints.

The resins supplied by Interplastics Corp. and Chemtron International are a thisotropic, rigid, corrosion resistant isophthalic resin specially formulated for fast bag wet our and even gel and cure. It is designed for the manufacture of isophthalic grade liner pipe using cure in place techniques for the relining of pipe intended for years of exposure to ambient temperature chemical solutions, as well as municipal sewage and water.

Installation

The tube is fabricated to a size that, when installed, will tightly fit the internal circumference and the length of the original conduit. Allowances are made for circumferential stretching during inversion.

CIPP Liner is installed by licensed general contractors with extensive experience in all types of sewer rehab work. The installation crews, experienced in sewer rehab, are further trained on the fine points of cured in place liners by working "hands on" with crews experienced with CIPP Liner.

The line is prepared for the CIPP Liner by completing all necessary spot repairs, removal of any obstructions, and a thorough cleaning with high pressure water. The service on the line is maintained with by-pass pumping if required.

The tube is vacuum impregnated with resin (wet-out) under controlled conditions. The volume of resin used is sufficient to fill all voids in the tube, provide nominal thickness and diameter, plus allow for polymerization and migration into cracks and joints of the original pipe.

The tube, after wet-out, is placed in the existing pipe through an existing manhole (or other approved access point) by means of an inversion process and the application of hydrostatic head sufficient to fully extend it to the next designated manhole or termination point. The tube is inserted into a vertical inversion standpipe with the impermeable plastic membrane side out. At the lower end of the inversion standpipe, the tube is turned inside out and attached to the standpipe so that a leak proof seal is created. The inversion head is adjusted to be of sufficient height to cause the impregnated tube to invert from point of inversion to point of termination and hold the tube tight to the pipe wall, producing dimples at side connections.

Care is taken during the inversion so as not to over-stress the felt fiber. A lubricant is used to reduce friction during inversion. This lubricant is poured into the inversion water in the down tube or applied directly to the tube. The lubricant is a nontoxic, oil-based product that has no detrimental effects on the tube, boiler, or pump system.

After inversion is completed, a suitable heat source and water re-circulation equipment are used to circulate heated water throughout the pipe. The equipment is capable of delivering hot water throughout the section to uniformly raise the water temperature above the temperature required to effect a cure of the resin. The heat source is fitted with suitable monitors to gauge the temperature of the incoming and outgoing water supply. Another such gauge is placed between the impregnated tube and the pipe invert at the termination point to determine the temperatures during cure.

Initial cure will occur during temperature heat-up and is completed when exposed portions of the new pipe appear to be hard and sound and the remote temperature sensor indicates that the temperature is of a magnitude to realize an exotherm or cure in the resin. After initial cure is reached, the temperature is raised to the post-cure temperature. The post-cure temperature is held for a period, during which time the re-circulation of the water and cycling of the boiler to maintain the temperature continues.

The new pipe is cooled to a temperature below 100 degrees F (38 degrees C) before relieving the static head in the inversion standpipe. Cool-down is accomplished by the introduction of cool water into the inversion standpipe water being drained from a small hole made in the downstream end. Care is taken in the release of head so that a vacuum does not develop that could damage the newly installed pipe.

After the new pipe has been cured in place, the existing active service connections are reconnected from the interior of the pipeline by means of a television camera and a remote-control cutting device.

For more information see our C.I.P.P. Corp. website.