How to Calculate Floatation Pipe

A pipe's buoyancy can put stress on weak sections.

A pipe floats when its buoyancy exceeds its weight. The buoyancy of high density polyethylene pipes, for instance, helps pontoons near docks stay afloat. Other pipes, however, such as those underground, are supposed to remain in a fixed place, and flotation when groundwater rises can damage the pipe. Engineers must calculate a pipe's flotation to predict how it will respond to changing water levels. They measure a pipe's tendency to float using Newtons, the standard scientific unit of force.

Instructions

1. Multiply the pipe's mass, in kilograms, by 9.81, the force of gravity on each kilogram. For example, if a pipe weighs 30 kg: 30 x 9.81 = 294.3 Newtons.

2. Multiply the volume of water that the pipe displaces, measured in liters, by 9.81. If the pipe submerges fully, this is the volume of the pipe. For example, if the pipe displaces 11.3 liters of water: 11.3 x 9.81 = 110.85 Newtons.

3. Subtract the answer to Step 1 from the answer to Step 2: 110.85 - 294.3 = -183.45 Newtons. This force represents the pipe's flotation.

References

• North Carolina State University; Engineering Field Manual; William Urquhart
• University of Rhode Island; Dredging Applications of High Density Polyethylene Pipe; Virginia R. Pankow

Resources

• University of Colorado: Buoyancy
• Oxford Plastics Inc; Floating Pontoons Using Hdpe Pipe; 2010