Page 198 - Trenchless Technology Piping Installation and Inspection

162 Cha pte r F o u r

Advantages Limitations
1. Resistant to both internal and 1. Sensitive to operating temperature,
external corrosion must be derated in case of long-
2. Gasket-joints and fusible joints term exposure to temperatures
have an excellent track record above room temperature
of leak-free performance. 2. Sensitive to ultraviolet light if
3. All four restrained-joint PVC exposure is greater than 2 years
products have high tensile (unless pipe is formulated with
strengths for HDD and other higher ultraviolet [UV]-inhibitor level)
trenchless processes 3. Less longitudinal flexibility than
4. Highly abrasion resistant for alternative thermoplastic piping
sewer applications material
5. Low internal frictional 4. Thinner-walled sewer pipe is
resistance for both pressure sensitive to bedding conditions.
and nonpressure applications 5. Susceptible to chemical permeation
6. At least 2.5 times stronger in cases of gross contamination
than other thermoplastic pipe 6. Susceptible to impact damage in
(higher stiffness, higher HDB) cold temperatures
7. Expansion is significantly 7. Susceptible to rapid crack
lower than in alternative propagation failure. Tapping of
thermoplastic piping material fused PVC pipe must be done with
extreme caution.

TABLE 4.11 Advantages and Limitations of PVC Pipe

development of PE pipe in the 1960s. Early PE pipe use was mainly
in the gas industry. Today, more than 95 percent of new and replace-
ment gas distribution pipe in the North American is PE pipe. Other
applications of PE pipe gradually spread to industrial and municipal
systems. Since the development of high-density PE materials in the
1970s, a significant use for PE is sliplining renewal of nonpressure
gravity sanitary sewers. The development of ASTM and AWWA
pressure piping standards led to the widespread use of PE pressure
pipe in municipal applications in North America over the past
decades. This is due to the recognition of the advantage of a corro-
sion resistant, fused pipeline in reducing water loss and pipeline
ruptures. Many municipalities that have already been specifying
another thermoplastic material, are using PE in trenchless and open-
trench installations. Open-cut waterworks projects are being per-
formed with PE pipe at an increasing rate. Also, the wider accep-
tance of trenchless technology construction methods for new
construction and renewal of water and sewer systems has placed PE
pipe at the forefront of the no-dig industry. Today, PE is the most