What feature on a tube ensures smooth exhaust flow by avoiding wrinkles during bending?

• A. Mandrel Bend
• B. Merge
• C. Formed
• D. Double-slip

Answer: (A)

Maintaining a round, undistorted cross-section through a bend is essential to avoid internal wrinkles that would disrupt smooth exhaust flow. A mandrel bend accomplishes this by placing a rigid mandrel inside the tube as it is bent. The mandrel supports the inner wall, preventing it from wrinkling or collapsing and keeping the diameter consistent along the bend. That smooth, uniform passage reduces turbulence and backpressure, improving exhaust flow and performance.

Other terms describe different aspects of exhaust systems: a merge refers to combining exhaust streams, which isn’t about maintaining wall shape; formed refers to bends made by forming processes, which can still wrinkle without internal support; double-slip describes a type of joint, not a bending technique.