Page 182 - Trenchless Technology Piping Installation and Inspection

Pipe and Pipe Installation Considerations 147

Advantages Limitations
1. Specialized work crew not 1. In open-cut construction, pipe is
required for installation sensitive to bedding conditions-
2. Large selection of available shear failure and beam breakage
nominal diameters may occur
3. Wide variety of pipe lengths 2. Handling and installation
available difficulty because of heavy weight
except where weight would be
4. Large selection of both
structural and pressure advantageous because of flotation
concerns
strengths
3. Susceptible to external corrosion in
5. Relatively low cost of
maintenance acidic soil environments
4. Highly vulnerable to hydrogen sulfide
6. Capability to withstand very
high pressures attacks and internal microbiological-
induced corrosion at crown.
7. Ideal for pipe jacking
A concern in sanitary applications
applications owing to high
only.
compressive strengths
5. Generally difficult to repair,
8. Internal corrosion can be
particularly in cases of joint leakage
significantly reduced by using
or failure in pressure pipes
thermoplastic lining
6. Tendency to leak because of high
9. External sulfate corrosion may
pipe wall porosity and shrinkage
be reduced by an additional
cracking
sacrificial wall thickness
7. Without internal lining, life span is
determined by the Pomeroy/
Parkhurst ‘AZ’ design method significantly reduced in the case of
sanitary sewer applications and only
is more commonly added to
the inside of the pipe wall to then if there is a high potential for
H S generation
counter the corrosion from 2
biogenically generated H SO . 8. Somewhat lower abrasion
2 4
Alternatively, it is possible resistance—internal scouring can
use Type V sulfate-resistant occur if solid content and flow
Portland cement. velocities are high
9. Reinforcements in PCCP can
corrode or fail without little or no
external evidence
TABLE 4.7 Concrete Pipe Advantages and Limitations
In trenchless installation, however, concrete pipe is much less
sensitive to bedding conditions in the circumferential direction. For
RCP, roughly 90 percent of the load bearing capacity of the soil/structure
“system” is in the pipe wall.
In terms of “beam breakage,” the statement is partially correct.
RCP is not designed for beam strength. But, that is the reason for the
relatively short joint lengths in use––so that one length of pipe may