State of Technology Report for Force Main Rehabilitation, Final ...
State of Technology Report for Force Main Rehabilitation, Final ...
State of Technology Report for Force Main Rehabilitation, Final ...
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On-Site Expandable PVC Close-Fit Lining<br />
Duraliner<br />
Duraliner from Underground Solutions is a patented, stand alone structural liner (Class IV) made <strong>of</strong> PVC<br />
and available in diameters <strong>of</strong> 6 to 30 inches (150 to 760 mm). Duraliner is NSF 61 certified, so it also is<br />
acceptable <strong>for</strong> potable water applications. Duraliner is a PVC pipe that meets all <strong>of</strong> the requirements <strong>of</strong><br />
AWWA C900 and C905 prior to modification by expansion. The final product meets the requirements <strong>of</strong><br />
AWWA C909.<br />
The outside diameter <strong>of</strong> the starting PVC pipe stock is sized smaller than the inside diameter <strong>of</strong> the host<br />
pipe. Sections <strong>of</strong> the Duraliner pipe are then butt-fused together <strong>for</strong>ming a continuous pipe. The pipe is<br />
then inserted into the cleaned and previously inspected host pipe. Special end caps are fitted to the ends<br />
<strong>of</strong> the pipe along with temperature sensors. The PVC pipe is heated with steam, and then pressure is<br />
applied to expand the material tightly against the walls <strong>of</strong> the host pipe. It takes approximately 90<br />
minutes to fully expand the stock pipe. After cooling, the end fittings are removed and the expanded new<br />
pipe cut to length and reconnected to the system. Insertion lengths ranging from 700 to 1,500 feet (213 to<br />
457 meters) are possible. The liner can even navigate through a 45° elbow. The expansion <strong>of</strong> the PVC<br />
reorients the molecular chain in the circumferential direction, thereby increasing the tensile strength.<br />
Underground Solutions states that the HDB increases from 4,000 to 7,100 psi (276 to 490 bar). This more<br />
than compensates <strong>for</strong> the reduction in wall thickness caused by the expansion. Molecularly oriented<br />
polyvinyl chloride (PVCO) pipe has been used in Europe <strong>for</strong> over 20 years.<br />
3.4.4 Cured-In-Place Pipe. The first installation <strong>of</strong> a CIPP product was in a 70 m length <strong>of</strong><br />
1,175 × 610 mm brick sewer in Hackney, East London. It was installed in 1971 and a small number <strong>of</strong><br />
other projects were undertaken by the inventor Eric Wood, and his partners Doug Chick and Brian<br />
Chandler, who <strong>for</strong>med Insitu<strong>for</strong>m Pipes and Structures, Ltd. be<strong>for</strong>e they licensed Edmund Nuttalls, a civil<br />
engineering contractor in 1973. Nuttalls Permaline Division per<strong>for</strong>med approximately 380 projects<br />
be<strong>for</strong>e they were bought back by Insitu<strong>for</strong>m Group in 1986. It is estimated that about 40,000 miles <strong>of</strong><br />
CIPP liners have been installed worldwide, perhaps 25,000 by Insitu<strong>for</strong>m companies.<br />
It is by far the leading method <strong>for</strong> the rehabilitation <strong>of</strong> gravity sewers. With the expiration <strong>of</strong> the original<br />
patent on CIPP, many new variants have been introduced. Figure 3-17 highlights the main differences<br />
based on tube construction, method <strong>of</strong> installation, curing method, and type <strong>of</strong> resin.<br />
The original CIPP product was a needled felt tube, impregnated with polyester resin, which was inverted<br />
into a sewer through a manhole and cured using hot water. Insitu<strong>for</strong>m still markets this product today <strong>for</strong><br />
gravity sewers. Interestingly, the developer <strong>of</strong> the original CIPP product was actually trying to develop a<br />
liner <strong>for</strong> rehabilitating pressure pipes. However, they found it easier to get trials in gravity sewers so the<br />
pressure aspect was <strong>for</strong>gotten until some 20 years later. Now, a multitude <strong>of</strong> new CIPP products can be<br />
classified as either semi-structural or fully structural <strong>for</strong> pressure applications. A few also have an NSF<br />
61 listing and can be used <strong>for</strong> potable water.<br />
For this report, discussion <strong>of</strong> the relevant technologies is organized into non-structural, semi-structural,<br />
and fully structural CIPP as outlined below. The tube construction, installation method, cure method, and<br />
resins used are discussed <strong>for</strong> each CIPP technology.<br />
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