When water is displaced, an upward force - called buoyancy - is created. If the buoyancy force created by the displaced water is greater than the weight of the object displacing the water, flotation will occur. For all pipe, the buoyancy force depends on the weight of the pipe, the weight of the liquid load carried within the pipe, the weight of the backfill above, and the weight of the displaced water. Compared to other pipe materials, the significantly greater mass of concrete pipe is a benefit when installing pipe where flotation may be a problem.

Flotation of concrete pipe

View an online learning guide on Flotation of Circular Concrete Pipe


Flotation of concrete manholes is calculated in a similar manner to flotation in concrete pipe. In areas where flotation is a concern, Inland Pipe can manufacture manhole sections with extended bases, helping to resist flotation by increasing the size of the failure cylinder and adding additional anchoring force by providing a cone of soil above the extended lip.

flotation of concrete manholes

View an online learning guide on Manhole Flotation