Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...

composite. More research on identifying or developing a better NDT method or equipment for in-situ
liner thickness measurement is recommended.
9.1.3.4 Flexural and Tensile Testing. The testing of flexural specimens for the structural
performance represented by the flexural strength and flexural modulus is often carried out since it can be
compared with the specified values in the ASTM F1216 standard. Tensile strength and tensile elongation
at break also have been measured values when structural liner performance is investigated. In this study,
other parameters such as the tensile modulus were also recorded. From the testing conducted so far, the
flexural modulus tests provided the most useful values for interpretation but, of course, that may not be
the case for all types of liner issues. The tensile elongation at break varied over a wide range in the tests
conducted. Typically, when flexural and tensile testing is carried out, all the parameters mentioned above
are easily measured and recorded and could prove useful in a larger data set for establishing correlations
among types of liner defects and the test values for each parameter.
9.1.3.5 Surface Hardness Testing. Surface hardness testing was found to reveal differences between
the hardness of the inner surface of a CIPP liner and its external surface and to reflect the low flexural
modulus value and the variability of the tensile elongation at break value of the Denver 48-in. upstream
liner sample. While few conclusions can be drawn from the surface hardness data collected to date, this
type of testing appears to hold promise for evaluation of liner properties – either as-installed or their
degradation over time. As a non-destructive test that could potentially be deployed in pipelines of 8-in.
diameter (and larger), such a test could provide a quantitative non-destructive measure of great value and
it is recommended that further investigations of data correlations and test adaptations to in-pipe
measurements should be pursued.
9.1.3.6 Material Composition Testing. It is considered very important in the assessment of liner
deterioration to find a test or set of tests that will shed light on chemical or physical changes occurring in
the liner material over time. Tracking the rate of such deterioration (in conjunction with other liner and
site characteristics) would provide important information in projecting the lifetime of a liner. In the pilot
study, no evidence of liner deterioration was seen in the Raman spectroscopy and differential DSC testing
that was carried out. This is either due to the lack of deterioration in the samples tested compared to the
virgin resins tested or because the test is not sensitive to any type of deterioration that may, in fact, be
occurring. It is recommended that these tests and/or similar forms of material testing be applied to
deliberately aged liner specimens to establish the signatures of particular forms of deterioration before
they be applied in a wider context for tracking liner performance in the field.
9.1.4 Recommendations for National Data Compilation and Management. The ultimate goal
of carrying out retrospective evaluations is to be able to provide better guidance to municipalities on the
long-term performance of the various rehabilitation technologies available to them. Table 7-3 provided a
summary of an overall structure that could be used for a database to accommodate the differences in the
types of technologies used and the specifics of those technology applications. It is suggested that the
categorization of the city experiences be able to be as detailed as the city data would allow, but would
also allow information capture at a broader level when only that level of information was available. As
discussed in Section 7.3, broad interpreted data from agency records, CCTV inspections, and condition
assessment databases need to be accessed in addition to well characterized, quantitative data from
retrospective liner testing or the use of specific NDT approaches to liner evaluation. However, it is not
intended that the database would attempt to include all of the individual CCTV or condition assessment
data that cities are collecting. Rather, the database proposed would contain the interpreted results from
agencies of the performance of rehabilitation technologies plus specific physical or NDT that addresses
liner performance or degradation.
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