Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...
Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...
Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...
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BW cont<strong>in</strong>ues to use CIPP, ma<strong>in</strong>ly <strong>in</strong> laterals. The current methods used are:<br />
• Installation: air <strong>in</strong>version 80%; water <strong>in</strong>version 15%; and pull-<strong>in</strong> and <strong>in</strong>flate 5%<br />
• Cur<strong>in</strong>g: steam 80%; hot water 15%; and UV 5%<br />
Recently, BW experienced a problem with a UV-cured <strong>in</strong>stallation. A l<strong>in</strong>er failed to cure properly for<br />
unknown reasons, but BW suspects that it was due to contractor <strong>in</strong>experience or equipment failure. The<br />
l<strong>in</strong>er was removed by cutt<strong>in</strong>g it <strong>in</strong>to small pieces, and successfully replaced with a similar UV-cured l<strong>in</strong>er.<br />
However, BW considers that such failures are a rarity and that the systems are generally reliable; the<br />
technology is adequate, but that the problems occur with <strong>in</strong>stallers. A committed and experienced<br />
<strong>in</strong>stall<strong>in</strong>g contractor is necessary.<br />
In order to ensure the quality <strong>of</strong> CIPP <strong>in</strong>stallation, BW has developed a specification based around the<br />
follow<strong>in</strong>g standards:<br />
• EN13566-1:2002: plastics pip<strong>in</strong>g systems for renovation <strong>of</strong> underground non-pressure<br />
dra<strong>in</strong>age and sewerage networks - General.<br />
• EN13566-4:2002: plastics pip<strong>in</strong>g systems for renovation <strong>of</strong> underground non-pressure<br />
dra<strong>in</strong>age and sewerage networks - L<strong>in</strong><strong>in</strong>g with CIPP.<br />
• ISO175:1999: plastics - methods <strong>of</strong> test for the determ<strong>in</strong>ation <strong>of</strong> the effects <strong>of</strong> immersion <strong>in</strong><br />
liquid chemicals.<br />
• EN1542:1999: products and systems for the protection and repair <strong>of</strong> concrete structures. Test<br />
methods.<br />
• A jett<strong>in</strong>g resistance test developed by BW.<br />
• The Darmstadt abrasion resistance test.<br />
Type test<strong>in</strong>g is required for all materials used. Tests stipulated are: stra<strong>in</strong> corrosion, creep, and chemical<br />
resistance. Samples from the <strong>in</strong>stallation are taken and tested <strong>in</strong> a third party laboratory for thickness,<br />
tensile modulus and watertightness. Post-<strong>in</strong>stallation CCTV survey is also required; it is l<strong>in</strong>ked to GIS<br />
data and the data is archived for future reference. L<strong>in</strong>ers are also pressure tested where their location is<br />
considered critical, for example under embankments where the consequence <strong>of</strong> failure is high.<br />
The above items are QA/QC data required from the contractor, but BW is mov<strong>in</strong>g to a system <strong>of</strong><br />
performance specification and requir<strong>in</strong>g a guarantee from the manufacturers <strong>of</strong> proprietary products that<br />
this can be met. Products will be allowed based on such guarantees and the performance risk placed on<br />
the vendor.<br />
BW has undertaken <strong>in</strong>spection <strong>of</strong> CIPP <strong>in</strong>stallations after a period <strong>in</strong> service. An <strong>in</strong>stallation from 1985<br />
compris<strong>in</strong>g 1.9 km (1.18 mi) <strong>of</strong> 12 mm (0.47 <strong>in</strong>.) thick 750 mm (30 <strong>in</strong>.) and 825 mm (32.5 <strong>in</strong>.) diameter<br />
l<strong>in</strong><strong>in</strong>g was <strong>in</strong>spected <strong>in</strong> 2002, i.e., after 17 years <strong>of</strong> service. The <strong>in</strong>spection was by CCTV only and no<br />
defects were noted. S<strong>in</strong>ce then, several further <strong>in</strong>spections by CCTV and man entry have been<br />
undertaken <strong>of</strong> this same l<strong>in</strong>e, and coupons taken. No defects were noted <strong>in</strong> the <strong>in</strong>spection.<br />
Coupons have been retrieved from certa<strong>in</strong> pipes when pieces have been dislodged by high pressure jett<strong>in</strong>g<br />
done for clean<strong>in</strong>g purposes, but have not been tested to establish their properties. This has raised<br />
concerns over jett<strong>in</strong>g for clean<strong>in</strong>g <strong>in</strong> CIPP-l<strong>in</strong>ed pipes. BW has addressed this through chang<strong>in</strong>g its<br />
operational procedures for jett<strong>in</strong>g by limit<strong>in</strong>g pressure and us<strong>in</strong>g specific designs <strong>of</strong> nozzle.<br />
C-18