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What is a Mandrel Test?



A mandrel test is the inspection inside underground pipes and sewer conduits. This happens generally after new construction or maintenance. This test is issued by the cities or states to test the public sewer lines.This test will show whether or not the pipe has bent under stress and pressure of the soil above. 


What Does the Mandrel Do?

Commonly know as pigging, mandrel inspections test flexible pipes for deflection or out of roundness. The mandrel is pushed or pulled through each pipe to locate problems. A mandrel is a tool made with metal rods and fingers that will stop itself when it encounters an issue or blockage. Proving rings are also used to verify that each deflection gauge is within its tolerance.



  • This is a steel mandrel with metal rods for digging through the pipes.






Deflection Testing and the Future of Pipe Inspection

Deflection testing is performed on clean pipes after the compaction of trench back-fill and prior to surface restoration. There are now more technologically advanced ways to do these tests such as with video pipe inspection. This is where a camera is sent through the pipes to locate the issue without digging up the property. This can save the owner money as well as keep their land intact. However, if a problem is located, minor digging may take place in order for repairs to be made.


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