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 ...
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
3.4.4.2 Semi-Structural CIPP Liners<br />
Hot Water/Steam Cured<br />
Insitu<strong>for</strong>m PPL ® (Pressure Pipe Liner)<br />
PPL was first introduced in 1995. Since then, 44 miles <strong>of</strong> PPL has been installed in the US. The<br />
interactive liner is available in diameters from 8 to 60 inches (200 to 1,500 mm), with the ability to span<br />
over small holes and gaps in a host pipe <strong>for</strong> pressures up to 200 psi (13.8 bar). Insitu<strong>for</strong>m has a special<br />
epoxy resin that is NSF 61 certified <strong>for</strong> potable water, otherwise vinylester is used. The tube is made <strong>of</strong><br />
Insitu<strong>for</strong>m’s standard non-woven felt tube, but with some special glass rein<strong>for</strong>cement included <strong>for</strong> added<br />
tensile and flexural properties. The initial flexural modulus <strong>of</strong> PPL is 250,000 psi (17,241 bar) and<br />
flexural strength is 6,500 psi (448 bar). For spanning over holes, the flexural strength is reduced to one<br />
third <strong>of</strong> the initial value <strong>for</strong> long-term per<strong>for</strong>mance. In addition, a factor <strong>of</strong> safety <strong>of</strong> 2 is utilized. The<br />
PPL sock is saturated either in the factory or on site. The tube is then positioned in the existing pipe<br />
using water pressure to invert the tube inside out and to <strong>for</strong>m a close-fit. PPL can be installed in lines<br />
with bends up to 90 o . Typical renewal lengths are from 200 to 1,000 feet (61 to 305 meters). After<br />
positioning, the tube is cured with circulating hot water. After curing, the liner is allowed to cool down to<br />
90 o F. The ends are cut and sealed using expandable stainless steel bands and elastomeric seals. After<br />
installation, the liner is CCTV inspected <strong>for</strong> any abnormalities. Samples are collected and tested to<br />
confirm that the physical properties meet the design assumption. Also, a pressure test to twice the<br />
operating pressure, or operating pressure plus 50 psi (3.4 bar) (whichever is least), is recommended.<br />
National Liner ®<br />
National Liner was introduced in 1995. National EnvironTech Group, the technology supplier <strong>for</strong><br />
National Liner, reports that over 200 miles <strong>of</strong> liner have been installed, with most <strong>of</strong> that <strong>for</strong> gravity sewer<br />
applications. National Liner has only been used <strong>for</strong> pressure pipe installations in the past few years. Two<br />
<strong>of</strong> the nationally licensed contractors have both reported using National Liner <strong>for</strong> sewer <strong>for</strong>ce main<br />
applications. National Liner does not have a NSF 61 listing, so it is not suitable <strong>for</strong> potable water.<br />
National Liner is available in diameters <strong>of</strong> 6 to 120 inches (150 to 3,000 mm), with wall thicknesses<br />
ranging from 4.5 to 33.5 mm (0.18 to 1.34 inches) with the standard felt tube. Greater thicknesses are<br />
reportedly possible. The liner is made <strong>of</strong> a non-woven, needled polyester felt that is shop or site<br />
impregnated with a polyester resin. For pressure applications, a vinylester resin is used. National<br />
EnvironTech Group <strong>of</strong>fers a maximum operating pressure <strong>of</strong> 50 psi (3.4 bar) with its standard felt tube,<br />
but higher pressures with a new glass fiber composite tube are reportedly under development. The liner<br />
with a felt tube would be considered a semi-structural liner (Class II/III), and, with the glass fiber,<br />
considered a fully structural liner (Class IV). National Liner is installed using the inversion method, with<br />
either a column <strong>of</strong> water or pressurized air. Either hot water or steam is used <strong>for</strong> cure depending on the<br />
method <strong>of</strong> inversion. Any excess resin mechanically locks the tube to the host pipe by filling in cracks.<br />
3.4.4.3 Structural CIPP Liners<br />
Paraliner PW and Paraliner FM<br />
A relatively new product, Paraliner was introduced by NOVOC Per<strong>for</strong>mance Resins, LLC in October<br />
2007. Approximately 10,000 feet (3,049 meters) <strong>of</strong> potable water mains were lined with Paraliner PW in<br />
2008. The liner is available in diameters <strong>of</strong> 6 to 96 inches (150 to 2,400 mm) and with thicknesses from<br />
0.18 to 2.07 inches (4.5 to 52 mm). Paraliner PW or FM is impregnated by the installation contractor<br />
with a 100% solids NOVOC vinyl ester resin that contains no styrene. The “green” solution has no EPA<br />
reportable components and is NSF 61 certified (by Underwriters Laboratory [UL]) <strong>for</strong> use in potable<br />
water. As a result <strong>of</strong> no styrene, curing times are reduced 30% to 50% over conventional CIPP liner.<br />
Minimal shrinkage due to 100% solids also ensures a tight fit to the host pipe. The tube consists <strong>of</strong> one or<br />
32