Which testing device is used to test new sewers for deflection and joints?

Which testing device is used to test new sewers for deflection and joints?

• A. Mandrel
• B. Rodder
• C. Poly pig
• D. Air bag

Answer: (A)

Testing sewers for deflection and joints is about checking the interior geometry of the installed pipe to ensure it wasn’t crushed or misaligned during construction. A mandrel is a device sized to a specific diameter that is drawn or pushed through the sewer to see if it can pass freely. If the mandrel passes without binding, the pipe’s deflection is within acceptable limits and the joints are likely sound. If it snags or binds, that indicates excessive deflection or poor joint integrity that needs attention before backfilling. The other tools have different purposes: a rodder is mainly used to locate or pull lines and assist with debris removal, a poly pig is used for cleaning and sometimes leak detection but not for measuring deflection, and an air bag checks for leaks by pressurizing the line rather than assessing deflection or joint tightness.

Testing sewers for deflection and joints is about checking the interior geometry of the installed pipe to ensure it wasn’t crushed or misaligned during construction. A mandrel is a device sized to a specific diameter that is drawn or pushed through the sewer to see if it can pass freely. If the mandrel passes without binding, the pipe’s deflection is within acceptable limits and the joints are likely sound. If it snags or binds, that indicates excessive deflection or poor joint integrity that needs attention before backfilling.

The other tools have different purposes: a rodder is mainly used to locate or pull lines and assist with debris removal, a poly pig is used for cleaning and sometimes leak detection but not for measuring deflection, and an air bag checks for leaks by pressurizing the line rather than assessing deflection or joint tightness.