What is a Mandrel Inspection test? Mandrel Testing also known as deflection testing is used to determine that the ovality (deflection or out of roundness) of flexible sewer pipe meets the design specification. The test will show whether the pipe has bent under stress and pressure of the soil above. All public and private thermoplastic storm sewer pipes for residential subdivision are inspected by our Storm Water Division and are mandrel tested for excessive defection no sooner than 60 days after

Pile Driving Part II: Pile Types and Guidelines - Pile Buck Magazine