Deflection Testing

The deflection gauge is pulled through the pipe from MH to MH.




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Nieltech provides independent Mandrel deflection testing on all Thermo-plastic pipe sewers ranging in size from 6" up to 24" in diameter. The mandrel deflection test must be performed after final backfill to road subgrade elevation has been placed.


The mandrel is cylindrical in shape, and constructed with an odd number of evenly spaced arms or prongs, minimum 9 in number. The minimum diameter of the circle scribed around the outside of the mandrel arms is equal to the allowable deflection of 5%. The contact length of the mandrel is measured between the points of contact on the mandrel arm or between sets of prongs.


The Deflection Test is conducted by pulling the test device through a completed sewer run, from manhole to manhole. If the Mandrel gets caught in the pipeline and cannot be pulled through the line (manhole to manhole) in one straight pass, the line will deemed as a fail. 

Nieltech offers Re-rounding services to correct issue on the failed Deflected PVC Pipes.


Deflection Gauges 6" to 24".


Deflection Gauge

Deflection Gauges

Deflection Gauges


Features & Benefits:

  • Features

    • Quick results

    • Accurate

  • Benefits

    • Know whether or not there was damage while filling trench

    • Know your pipes meet spec

    • Avoid future problems caused by deflected pipes


75 Moorefield St. Cambridge, ON, N1T 1S2
Phone: (519) 748-0311
Fax: (519) 740-4242