State of Technology Report for Force Main Rehabilitation, Final ...

Another new technology that is being used for the repair of pre-stressed concrete cylinder pipes that have
experienced wire breaks is the use of a carbon fiber composite on the pipe interior surface. The internal
surface has to be cleaned and then roughened, usually with water blasting. After roughening, the surface
is dehumidified to ensure a good bond with the epoxy resin. There are two approaches to the application
of the carbon fiber textile. Pipe Medic is a patented composite material available from Quake Wrap
where the carbon fiber is already embedded in a pre-cured epoxy resin. It resembles wall paper. A layer
of epoxy adhesive is applied to the PCCP internal surface and then the Pipe Medic sheet is uncurled and
rolled into the epoxy. The more traditional method of use has been to wet out the carbon fiber with epoxy
resin just before application and then apply the uncured epoxy and carbon fiber composite to the interior
surface. NSF 61 certified epoxy top coats are applied over the composite for potable water applications.
3.3.2.2 Sleeve. Link-Pipe, a Canadian manufacturer
of trenchless pipe repair products, has a product available
for use in a pressurized system (Figure 3-3). Pressure-
Seal Sleeves are available in diameters from 4 to 54
inches (100 to 1,350 mm), and standard lengths of 12, 18,
24 and 36 inches (300, 450, 600, and 900 mm). Pressure-
Seal is designed for sealing pressure pipes up to 150
pound per square inch (psi) (10.3 bar) and it is uniquely
suitable for old CI mains that have unpredictable variations
in manufacturing tolerances, roundness, and joint offsets to
which the sleeve will conform. Each sleeve is specifically
manufactured for each location so it is important to get an
accurate measurement of the inside diameter of the pipe.
Some problems have been reported when the diameter was not
closely measured.
The sleeve core is made of stainless steel SST-316 with internal locking mechanism. An outside gasket is
saturated with sealant that is mechanically pressed against the host pipe when the sleeve is expanded and
locked in place. The sealant is ambient temperature cured and seals the sleeve in place, creating a
mechanical bond by filling surface roughness as well as chemical adhesion, thus sealing the joints and pin
holes. Link-Pipe has other trenchless repair technologies (e.g., Link-Pipe PVC), but these are not for
internal pressurized systems, rather they are designed to resist external soil loads.
3.3.2.3 External Repair Clamps. The second most
common method of repairing a break in a sewer force main,
aside from open cut replacement, is to place a full
circumferential repair clamp over the damaged section (Figure
3-4). The clamp must be wide enough to seal on adjacent pipe
wall that is structurally sound. If the wall is not sound, then
replacement is the only viable solution. There are a wide
variety of repair clamps, some coming in multiple pieces so
they can be placed around a damaged section of pipe without
removal of the pipe.
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Figure 3-3. Link-Pipe 12 inch
Pressure-Seal
Figure 3-4. Romac SS2
Repair Clamp