How do I fix a stripped TDC or Ductmate corner bolt?

For TDC/Ductmate, the corner pieces help hold and locate the flange joint, but they are not what makes a crooked run acceptable. Get the duct sections level and aligned first, with gasket on one flange face only, then seat the corners and tighten evenly. A corner can look a little ugly and still work; a duct run that is twisted, racked, or out of level will keep fighting every joint after it.

Stop if

• Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.

Check

• A loose corner can become a high-velocity leak, noise point, or pressure-test failure.

Steps

• Confirm which corner stripped and whether the flange is bent or misaligned.
• Check gasket placement at the corner and whether the joint is pulling evenly.
• Remove bad hardware and inspect the corner piece.
• Use shop-approved replacement hardware/backing method.
• Recheck clips, corners, and sealant after tightening.

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