Which seam type should be avoided when using aluminum duct?

Which seam type should be avoided when using aluminum duct?

• A. Button punch snap lock seams
• B. Crimped seams
• C. Lap seams
• D. Interlocking seams

Answer: (A)

Aluminum duct benefits from seams that keep the metal continuous and resist tearing, because aluminum is soft and prone to damage at punched features. The button punch snap lock seam relies on punching a small boss into the seam to lock it, which creates a localized weak point. In aluminum, that punched area can crack or deform under use, leading to leaks and reduced seam strength. Other seam types like crimped, lap, or interlocking joints don’t require punching through the material; they clamp or interlock the edges and distribute stress more evenly, providing a tighter, more durable seal for aluminum duct.

Aluminum duct benefits from seams that keep the metal continuous and resist tearing, because aluminum is soft and prone to damage at punched features. The button punch snap lock seam relies on punching a small boss into the seam to lock it, which creates a localized weak point. In aluminum, that punched area can crack or deform under use, leading to leaks and reduced seam strength. Other seam types like crimped, lap, or interlocking joints don’t require punching through the material; they clamp or interlock the edges and distribute stress more evenly, providing a tighter, more durable seal for aluminum duct.