Make a replacement S-lock

Before you start

• Verify field fabrication of the S-lock is allowed for the project and pressure class.
• Identify the required material, gauge, profile, and finished length from an approved sample or detail.
• Use clean, undamaged sheet stock.

Lay it out

1. Measure the duct width and required end allowance.
2. Mark fold lines accurately so both channels grip the duct hems.
3. Plan the lock orientation before forming.

Set and support it

1. Use a brake or approved forming method on a stable work surface.
2. Keep the strip straight during forming; a bowed cleat will not engage evenly.

Make the connection

1. 1

   Cut the strip to the required width and length.

2. 2

   Deburr all cut edges.

3. 3

   Form the first return and center web, then the second return to create the correct S profile.

4. 4

   Test the cleat on scrap or the duct edge without forcing it.

5. 5

   Adjust only with controlled forming tools.

6. 6

   Install it and complete the joint using the normal S-and-drive sequence.