Pipes Under Pressure
Excessive seismic movements can cause brittle failures in rigid pipes such as RCP. These failures can lead to fracturing and cracking propagation. In addition the low tensile strength and low resistance to shear forces and lateral movement causes failures among rigid pipe.
CSP joints must comply with the mechanical requirements of ASTM A798. This provides minimum values for joint performance including shear, movement, and pull-apart capacity. Rigid pipe, such as RCP, does not have such a requirement. Because RCP joints possess minimum resistance to pull-apart forces, their ability to withstand lateral movement and loads resulting from differential settlement is severely diminished.
Corrugated Steel Pipe can be used as slip lining for the failed concrete structure by sliding the CSP inside on skids or rails and using internal bands then grouting the gap between the concrete and metal structure.
During heavy downpours water can start to saturate the backfill material causing it to lose structural support. Once the backfill material becomes unstable it can eventually wash away leaving the pipe or bridge unsupported. Without any support the pipe can wash away or become damaged.
Properly backfilled and installed steel pipe/structures can perform well when flooding occurs. When properly installed, steel will not float unlike alternative plastic pipes. Steel can be designed with a variety of end treatments to help facilitate water running through the pipe/structure vs. underneath or into the backfill zone – which could wash the pipe away.
Steel is easy to handle, quick to manufacture and quick to install. Heavy equipment is typically not needed when installing CSP whereas heavier pipe such as concrete usually requires heavy construction equipment. The use of mobile mills for on site fabrication helps to cut down on construction times even more!
Corrugated steel is gaining wider appeal for special uses because the aluminized steel used in these structures is both long lasting, structurally sound, and relatively inexpensive compared to other product options.
CSP structures exceed the standards set by FEMA 320 and FEMA 361. These durable structures can be built with an attached steel door for installations in the side of an embankment, or with vertical access risers. A variety of access stubouts can be attached to the structure to allow the owner to install ventilation systems or even electrical systems.