American Underground, Inc. uses mandrel testing to ensure sewer pipe meets ASTM specifications D3034 and F679.

What is a Mandrel Test?

A mandrel test (also known as mandrel deflection test) is an important inspection to determine suitable clearance in sewer pipes. This test establishes that the ovality of a sewer pipe meets all specifications.  If there is any deviation or deformity of the sewer pipe, it could result in delays and costly replacements.

This testing ensures that flexible sewer pipe has been properly bedded and backfilled (ASTM D2321) as it’s critical to optimal and long-term performance for newly installed sewer lines.
Our top of the line aluminum gauges utilizes a nine arm (fin) design to ensure the pipe is tested accurately. Because of this unique design, gravel and debris are easily able to pass through. Other gauges can get hung up, causing a deflection test to fail, even though the pipe is within tolerance. Sized to .01″, both deflection gauge styles meet ASTM requirements.

A mandrel test requires the mandrel to be pulled through the sewer pipeline, from manhole to manhole. To successfully complete a mandrel inspection of a pipe, the device must pass freely through a sewer run. If the mandrel gets stuck or is caught anywhere within the pipe, the mandrel inspection issues a failing grade. determined a fail. If a pipe fails a mandrel test, it will need to be removed and reinstalled, or replaced completely. The pipe will then be subject to an additional mandrel inspection.  Contractors are responsible for the costs and delays associated with a failed mandrel test.

Mandrels, AKA Deflection Gauges

Mandrels are also called deflection gauges. Deflection is the degree to which an element of the pipe changes shape when a load is applied. The mandrel test is completed on sewer pipes and also in road construction. Deflection testing is performed by dragging a sewer mandrel through a pipe. For sewage pipes, all mandrel testing is completed in accordance with city and county regulations and is critical to ensure long-term performance of sewer lines.

Mandrels/deflection gauges are available in different sizes, and can be used to test sewer pipes for deflection. The use of these gauges and tests helps verify that the sewer pipes have been properly installed and remain rounded.

Mandrel Features

American Underground has different types of deflection gauges or mandrels that are used in sanitary sewer testing.

We offer two different designs, nine arms or fin shaped that are evenly spaced allowing for gravel and other debris to pass freely through the tool

Features of Fin Style Gauges

  • Lightweight and corrosion-resistant
  • Top of the line aluminum gauges utilizes a nine-fin design
  • Gravel and debris are able to pass through
  • Can be verified by inspectors with no proving ring required
  • Sized to .01″, meets ASTM requirements

Features of Arm Style Gauges

  • Top of the line aluminum construction
  • Corrosion-resistant
  • Open design allows for debris to pass through
  • A proving ring must be used to determine the mandrel diameter
  • Sized to .01″, to meet ASTM requirements
Example of a mandrel used in mandrel testing.
Sewer mandrel for deflection testing
A Diagram Of A Mandrel Test

Chicago Mandrel Testing Experts

American Underground knows the importance of comprehensive testing of sewer mains with mandrels.  For over 30 years, we’ve been servicing the Cook County area with best-in-class service for homeowners and businesses. Conveniently located in Wheeling, Illinois we are the leader in high-quality sewer inspection, cleaning, & maintenance services to customers in the Midwest and beyond. Give us a call at 847-724-3503 or contact us for more information.