E.
F.
The Contractor shall ensure that the pressure in the liner exceeds both the pressure
due to the groundwater head and any pressure due to sewage in laterals or
connecting side sewers
A pre-liner may be installed prior to liner inversion in sewers with infiltration or
missing pipe sections.
CURING
1. After insertion of the tube is complete, the Contractor shall provide a suitable
heat source and distribution system to circulate hot water, air, and/or steam
through the pipe as recommended by the manufacturer. The equipment shall
be capable of delivering hot water, air, and/or steam to uniformly raise the
temperature above that required to cure the resin. This temperature shall be
determined by the manufacturer based on the resin/catalyst system employed.
2. The heat source piping shall be fitted with suitable continuous monitoring
thermocouples to gauge the temperature of the incoming and outgoing curing
medium. The temperature of the curing medium shall meet the requirements
of the resin manufacture as measured at the heat source inflow and outflow
return lines. Additional continuous monitoring thermocouples shall be placed
between the impregnated felt tube and the pipe invert at the manholes. The
curing medium temperature in the line during the cure period shall be as
recommended by the resin manufacturer. Care shall be taken during the
elevated curing temperature so as not to over stress the liner materials.
3. Initial cure shall be deemed to be completed when inspections of the exposed
portions of liner appear to be hard and sound and the remote temperature
sensor indicates that the temperature is of a magnitude to realize an exotherm.
The cure temperature shall be held for the period recommended by the resin
manufacture, during which time the distribution and control of the curing
medium shall continue. Curing the CIPP shall consider the host pipe material,
resin/catalyst system, ambient temperature, moisture level, and thermal
conductivity of the soil.
COOL-DOWN
The Contractor shall cool the hardened liner to a temperature below 100 degrees F
before relieving the pressure in the section. Cool-down may be accomplished by
the introduction of cool water or air into the lined pipe to replace water or steam
and water being drained. Water shall be drained from a small hole made in the
downstream end. Care shall be taken in the release of the static head or air
pressure so that a vacuum will not be developed that could damage the pipe or the
newly installed lining. After the tube is cured, a cool down period shall be used
prior to opening the downstream plug and returning normal flow back into the
system.
02650-8
