Underground Infrastructure - August 2023 - 25

CURRENTLY @ CUIRE
urea elastomeric material, and the lining
system passed 500 psi pressure without
failure. Th e 4- and 6-inch holes spanning
testing is still in progress.
In addition, CUIRE is working on the
short-term external buckling test to determine
the liner resistance against the
buckling eff ect due to external hydrostatic
pressure. Both the short-term hole
spanning and external buckling tests,
along with the vacuum pressure test, will
confi rm the liner structural properties,
as per class II and III. FIGURE 2 shows
the hole-spanning test setup in progress.
FIGURE 3 represents the complete
hole-spanning test set up with a hydrostatic
pump assembly.
Th e short-term hydrostatic burst test
is helpful to confi rm the liner integrity,
assuming the liner has no support from
the host pipe, or the host pipe completely
deteriorates. Liner pipe samples can be
cast with the rig systems or sonotube and
tested under a desired working pressure
over a short period of time to determine
the liner resistance, without the support
of a host pipe. Burst pressure testing can
be employed by the manufacturer to
qualify the SAPL material under the defi
ned pressure class, similar to the PVC
pipe manufacturing industry.
Since the liner material applied to the
host pipe decreases the internal pipe diameter,
it is important to compare the hydraulic
fl ow characteristics with fl ow characteristics
of the host pipe without liner,
noting the improved surface smoothness.
Th is is an important consideration in
pressure pipe relative to pumping needs.
Long-term full-scale
laboratory testing
Th e tests presented in TABLE 5 are suggested
tests that can be performed to
determine the creep behavior of the liner
over a longer period of time, i.e., approximately
10,000 hours in pressure pipe application.
Th ese tests will also be helpful
for predicting the design life of the liner.
Th e long-term hole spanning internal
hydrostatic pressure is similar to the
short-term hole spanning test. Th e diff erence
between the two tests is the period
FIGURE 2. Hole-spanning test setup in progress
of time for which the pressure needs to
be held. Th e test can determine the longterm
capacity of the hole spanning at the
desired hydraulic pressure.
Th e long-term pipe burst hydrostatic
design basis test can be performed for
10,000 hours. Th e data obtained from
this test can be used to extrapolate 50
years of design life of the liner. Fatigue
full-scale laboratory tests can be performed
on the liner pipe samples and
provide loading to the pipe samples for
the desired number of cycles.
Pipelines subjected to cyclic stresses
weaken more rapidly than those operating
under steady pressure. Hydraulic
pressure surges, transients and water
hammers are important considerations
for SAPL design in water transmission
and distribution systems relative to fatigue
behavior of the liner. Results from
fatigue testing determine if the liner can
withstand cyclic loads that are 1.5 or 2
times higher than its pressure class for 2
million or more cycles, as well as predict
design service life.
Th is article presented the testing requirements
needed for the evaluation
and certifi cation of polymeric SAPL in
gravity and pressure pipe applications.
It can help partitioners use diff erent
test methods and certify the polymeric
SAPL in diff erent fi eld conditions, as per
structural classifi cation for the renewal of
gravity and pressure pipes application.
Since there is not enough testing and
research done on the SAPL for structural
FIGURE 3. Short-term hole spanning
complete test setup
capabilities,
practitioners have limited
confi dence in using the SAPL material
as a structural material in pressure pipes.
Material testing is key to understanding
the material's properties and its behavior
in diff erent fi elds and environmental
conditions. In addition, having these
properties gives a more reliable design
of the liner system for both pressure and
gravity application.
Future plans include consideration of
extreme temperature and environmental
conditions during testing.
REFERENCES
Najafi , M. and Gokhale, S. (2022).
Trenchless Technology.
McGraw-Hill Education.
UndergroundInfrastructure.com | AUGUST 2023 25
http://www.UndergroundInfrastructure.com
Underground Infrastructure - August 2023

Table of Contents for the Digital Edition of Underground Infrastructure - August 2023
