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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Table 3-3. Properties <strong>of</strong> Hunting Polyurea Spray-on Linings<br />
Tensile (ASTM D638) Flexural (ASTM D790)<br />
Strength Modulus Elongation Strength Modulus Shrinkage<br />
Type<br />
psi psi %<br />
psi psi<br />
%<br />
Flexible HE800 1,700 1,200 800 1,400 22,500 0<br />
Semi-Structural<br />
SS100<br />
3,400 41,200 100 4,300 93,000 0.5<br />
Fully Structural<br />
FS250<br />
12,000 160,000 20 9,300 250,000 1<br />
3M<br />
3M Water Infrastructure has announced a new product, Scotchkote Spray In Place Pipe (SIPP) 269<br />
Coating, which is a patent pending-polyurea blend. The Scotchkote SIPP 269 Coating just received<br />
certification against NSF 61 <strong>for</strong> use in potable water applications. The reference to a coating is<br />
misleading as the material is actually intended to be used as a liner. Little technical data were available at<br />
the time <strong>of</strong> this report. It is understood that the Trenchless <strong>Technology</strong> Center (TTC) will be conducting<br />
some long-term per<strong>for</strong>mance tests on this polyurea material.<br />
Nano-Enhanced Polyurea<br />
The TTC at Louisiana Tech University is working with one vendor <strong>of</strong> polyurea resins to develop a nanoenhanced<br />
version <strong>of</strong> polyurea, which would have even higher flexural modulus, well above the 250,000 to<br />
375,000 psi (17,241 to 25,862 bar) achievable with today’s standard technology. The trade <strong>of</strong>f with the<br />
higher modulus is a lower elongation, but 5% elongation should be adequate <strong>for</strong> most pipe rehabilitation<br />
projects.<br />
3.4.3 Close-Fit Lining Systems. The use <strong>of</strong> close-fit liners is <strong>of</strong>ten called modified sliplining. It<br />
involves the use <strong>of</strong> a thin walled PE liner with an outside diameter that is similar to the inside diameter <strong>of</strong><br />
the host pipe. The key to installing the liner is to temporarily reduce the liner diameter to facilitate its<br />
insertion into the host pipe. Once the liner is in place, it is reverted back to its original outside diameter<br />
<strong>for</strong>ming a close-fit to the host pipe. The reinstatement <strong>of</strong> connections and fittings <strong>of</strong>ten requires special<br />
techniques and fittings.<br />
As shown in Figure 3-9, close-fit liners can be classified into two broad categories including those that<br />
achieve temporary diameter reduction through: (1) a symmetrical reduction process; and (2) a fold-and<strong>for</strong>m<br />
process. In the case <strong>of</strong> the symmetrical diameter reduction process, these can rely upon either axial<br />
tension or radial compression to reduce the diameter. Fold-and-<strong>for</strong>m liners, depending on diameter, can<br />
be pre-folded and coiled into spools at the factory or de<strong>for</strong>med on site.<br />
Close-fit liners are usually thin walled (standard dimension ratio [SDR] > 33) so they maximize the<br />
retention <strong>of</strong> flow cross-section. There are a range <strong>of</strong> products from which to choose including thin semistructural<br />
liners to thicker fully structural liners. On the other hand, most liners are “non-standard” PE<br />
diameters and require special fittings. Many <strong>of</strong> the early technologies came from the UK and were<br />
subject to licensing and other commercial arrangements with international companies.<br />
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