Page 142 - Trenchless Technology Piping Installation and Inspection

108 Cha pte r T h ree

2. Bypassing water flow.
3. Thoroughly cleaning existing pipe and removing all films,
loose materials, debris, and silt prior to the lining.
4. Inserting the lining head connected to the lining rig into the
pipe.
5. Supplying mortar to the machine through high-pressure
hoses and ensuring uniform application of lining from the
sprayer at a constant speed.
6. Troweling of the applied cement-mortar with either rotating
trowels or spatulas attached to the lining head.

After the completion of the application, the lining is cured in a con-
trolled environment to prevent rapid loss of moisture. Usually CCTV
or another inspection method is used to inspect quality of installa-
tion. Table 3.5 represents advantages and limitations for cement-
mortar lining methods.
3.16.2 Epoxy Linings
Epoxy lining was first introduced in the United Kingdom in the
late 1970s and introduced in the North America in the early 1990s.

Advantages Limitations
1. Minimum service 1. Bends, valves, and fittings must be
interruption compared removed prior to lining.
to other pipe renewal 2. Bypass is required.
methods.
3. Curing time is dependent on curing of
2. Protects deterioration cement and may take a long time.
of pipe against further 4. Dependent on the lining thickness, there
corrosion. may be a slight reduction of pipe internal
3. For worker-entry pipes, diameter.
reinforcement can be 5. Does not enhance structural integrity of
used to provide structural the pipe.
support (shotcrete and 6. Cement-mortar lining may result in high
gunite).
pH water.
4. Usually entry and exit
7. Usually plugs ¾ in. or less valves or
pit is required, no major
lateral connections.
excavation is necessary.
8. Quality and durability of installation
5. Usually flow capacity
is dependent on the adhesion to the
is improved due to
internal surface of the existing pipe,
smoothness of lining
which in turn is dependent on the degree
surface compared to the
the existing pipe cleaned.
original surface of the
existing pipe.
TABLE 3.5 Advantages and Limitations for Cement-Mortar Linings