Concrete pipe derives most of its strength from the pipe material itself, not the surrounding soil. This means that the structural performance of the pipe is the concrete pipe supplier’s responsibility. Consequently, risk to the designer and installer is minimized.
Flexible pipe has little inherent structural strength. In fact, the majority of strength in flexible pipe is built on-site in the soil envelope. As incorrectly installed flexible pipe is prone to failure, the structural performance of the installed flexible pipe (and the risk that goes with it) is taken on almost exclusively by the designer and installer.
The following educational journal Structural Deformation Characteristics of Installed HDPE Circular Pipelines shows how flexible pipe tends to fail at an alarming rate. In fact, the study shows that 63% of the 98 pipelines tested had deformation in excess of the specified limit. In addition ovality, crown flattening, buckling, and inverse curvature (snap through) failures were observed.
Specifying and installing concrete pipe is an excellent way to avoid unnecessary risk and dependence on the quality of installation.