A pipe defection test, also known as mandrel test is performed to verify that a flexible sewer pipe meets municipal design specifications by measuring its deflection (ovality) under installed conditions. This test ensures that the pipe has not deformed beyond allowable limits and confirms proper installation, helping to maintain long-term structural integrity and prevent costly future repairs.

During testing, a calibrated mandrel (deflection gauge), manufactured to a diameter specified by the municipality, is inserted into the sewer line at one access point and pulled through to the opposite end. At the same time, a mainline CCTV inspection is conducted to visually record the testing process in real time.

The CCTV footage serves as confirmation of a successful test or assists in identifying and locating any defect where the mandrel cannot pass, indicating excessive deflection or possible installation deficiencies.

If the mandrel is successfully pulled through the full length of the pipe without obstruction, the installation is deemed to be in compliance with municipal standards. While simple in execution, the mandrel test is a reliable and widely accepted method for evaluating pipe deflection and overall installation quality.

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