In sewer construction, a mandrel is used to check for deflection in pipes.

In sewer construction, a mandrel is used to check for deflection in pipes.

• A. Hydrostatic test
• B. Manhole test
• C. Sewer taps
• D. Deflection test

Answer: (D)

Deflection checks are used to verify that a pipe hasn’t bent or narrowed beyond what’s acceptable after installation. A mandrel is a cylindrical plug of a precise diameter that is pulled or pushed through the pipe to test its interior against deformation. If the mandrel passes easily, the pipe’s deflection is within allowable limits; if it binds or meets resistance, the pipe has deflected too much, usually from settlement, improper bedding, or excessive load. This simple pass/fail helps ensure the sewer line will carry flow without excessive friction or future issues. Hydrostatic testing checks for leaks by filling with water and pressurizing; manhole testing evaluates the watertightness of manholes; sewer taps refer to lateral connections rather than testing.

Deflection checks are used to verify that a pipe hasn’t bent or narrowed beyond what’s acceptable after installation. A mandrel is a cylindrical plug of a precise diameter that is pulled or pushed through the pipe to test its interior against deformation. If the mandrel passes easily, the pipe’s deflection is within allowable limits; if it binds or meets resistance, the pipe has deflected too much, usually from settlement, improper bedding, or excessive load. This simple pass/fail helps ensure the sewer line will carry flow without excessive friction or future issues. Hydrostatic testing checks for leaks by filling with water and pressurizing; manhole testing evaluates the watertightness of manholes; sewer taps refer to lateral connections rather than testing.