Which testing device is used to verify sewer lines for deflection during construction?

Which testing device is used to verify sewer lines for deflection during construction?

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

Answer: (C)

Testing for deflection in installed sewer lines means checking that the pipe hasn’t bent or deformed beyond what the design allows, so flow stays smooth and joints stay tight. A mandrel is sized to fit the pipe’s inside diameter and is pulled through the completed line. If it passes without resistance, the pipe’s internal shape is within allowable limits. If it binds, there’s excessive deflection or an obstruction that needs repair before backfill. This direct pass/fail check of the pipe’s inside geometry is why the mandrel is the best choice for verifying sewer lines for deflection during construction. The other tools serve different purposes: a rodder helps with pulling or clearing lines, a poly pig cleans or surveys from the inside, and an air bag is used for seating or testing joints or for lifting/positioning, not for measuring deflection.

Testing for deflection in installed sewer lines means checking that the pipe hasn’t bent or deformed beyond what the design allows, so flow stays smooth and joints stay tight. A mandrel is sized to fit the pipe’s inside diameter and is pulled through the completed line. If it passes without resistance, the pipe’s internal shape is within allowable limits. If it binds, there’s excessive deflection or an obstruction that needs repair before backfill. This direct pass/fail check of the pipe’s inside geometry is why the mandrel is the best choice for verifying sewer lines for deflection during construction. The other tools serve different purposes: a rodder helps with pulling or clearing lines, a poly pig cleans or surveys from the inside, and an air bag is used for seating or testing joints or for lifting/positioning, not for measuring deflection.