TinnerFlow
S-and-Drive Square Duct · Bent S-lock

Replace bent S-cleat

Damaged top/bottom lock

Task typeBent S-lock
Tools / equipmentReplacement S-lock, stretcher, hammer

Before you start

  • Inspect whether only the S-cleat is bent or the duct hems are crushed as well.
  • Support and unload the joint.
  • Have a correct replacement cleat ready before opening the connection.

Lay it out

  1. Check the full top or bottom width for damage.
  2. Verify the replacement profile and length match the duct construction.

Set and support it

  1. Clamp or support the sections so they remain aligned when the side drives are removed.
  2. Prevent the loose section from dropping when the S-cleat is pulled.

Make the connection

  1. 1

    Remove or back out the side drives as needed.

  2. 2

    Separate the sections only enough to remove the damaged S-cleat.

  3. 3

    Straighten minor duct-hem damage with proper hand tools.

  4. 4

    Install the replacement S-cleat across the full width.

  5. 5

    Bring the sections together square and reinstall the drives.

  6. 6

    Finish, seal, and recheck the support.

Check the install

  • The replacement cleat captures both duct hems for the complete width.
  • The duct edges are not cracked or thinned.
  • The joint closes evenly at all corners.
  • The repaired joint remains square after support is released.

Common mistakes

  • Hammering a crushed S-cleat flat while it is still on the duct.
  • Replacing the cleat without checking the duct hem.
  • Opening the joint while one section is unsupported.
  • Using a cleat with the wrong profile or gauge.

Stop and ask

Stop if the duct hem is split, the corner is crushed beyond repair, or the correct cleat profile is unavailable.