SWM Info

Facts About Deflection


Deflection occurs in pipes, mainly construction pipes, that are under a lot of pressure. The most common situation is when a flexible pipe, such as a polymer or plastic-type, bends too far out of its shape to be useful or safe. The accepted flexibility for pipes that are not rigid is 2%, meaning anymore and it is prone to break down or otherwise be unusable. Flexible pipes are made of different materials than rigid pipes, which leads to another set of problems.

Underground Pressure

Pipes under pressure gradually bend into an oval shape. How distorted the oval shape is can be detected by measuring the ring or change in diameter. This often happens within the first couple months of a pipe being underground, but can sometimes occur later on as time goes by. Often, a pipe will change shape multiple times before settling into one form. Therefore, it is important to test for distortion to know for sure whether or not the pipe is too distorted to use. 

Useful Tools

One such way is by using deflection gauges to measure the shape. Stress tests and other tests often help workers understand if the pipe has changed at all. A certain amount of flexibility is generally accepted since other factors like the weather or the type of pipe can influence the deflection. Sometimes the pipe even bends due to its own internal pressure, which is a problem that can be fixed if workers know about it. 


The dangers of deflection cannot be overstated. A pipe can burst if not properly treated. In addition, it could crack or slowly corrode over time if not maintained. It can be hard to tell if a pipe is under too much pressure from only viewing it, so deflection gauges and other instruments that you can measure deflection with are crucial for this testing.