What is the primary purpose of a mandrel in sewer work?

What is the primary purpose of a mandrel in sewer work?

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

Answer: (B)

A mandrel is used to check for deflection in sewer pipes. By pulling a smooth cylindrical plug through the installed pipe, inspectors see how much the pipe sags or bends between supports and bends. If the deflection exceeds allowable limits, the pipe can lose capacity and flow may be obstructed, signaling installation issues that need correction before backfilling. This test focuses on the pipe’s geometry and integrity, not on leaks or taps. That’s why the primary purpose is deflection testing.

A mandrel is used to check for deflection in sewer pipes. By pulling a smooth cylindrical plug through the installed pipe, inspectors see how much the pipe sags or bends between supports and bends. If the deflection exceeds allowable limits, the pipe can lose capacity and flow may be obstructed, signaling installation issues that need correction before backfilling. This test focuses on the pipe’s geometry and integrity, not on leaks or taps. That’s why the primary purpose is deflection testing.