Page 151 - Trenchless Technology Piping Installation and Inspection

Coatings and Linings for Potable W ater Pipe Distributions 117

FIGURE 3.13 Six inch ID fractured cast iron pipe previously lined with polyurea.

FIGURE 3.14 Six inch sheared cast iron pipe previously lined with polyurea.

loading and, thereafter remain intact and bridging the crack left after
fracture. This requires the structural enhancing liner to have enough
elongation, as well as cohesive strength that exceeds the adhesion of
the lining to the existing pipe. Class 2 and 3 should meet these
requirements.
After a pipeline has failed by transverse or shear fracture, move-
ment of the pipe can continue at that point. The lining must therefore
be able to accommodate such movement which can take the form of
angular deflection.
Figures 3.13 and 3.14 illustrate the results. The assembly is sub-
jected to a three-point flexural loading in a universal testing machine.
Displacement controlled loading was applied and the deflection of
the joint monitored as a function of load.

3.20 Summary
This chapter focused on spray-on coating and lining methods for
renewal of potable water distribution pipes. Potable water pipe
renewal is relatively a new market for trenchless renewal methods.
These methods have many advantages over other trenchless renewal