Playbook
Before Sealing a Flange Leak
Use before mastic/tape/caulk gets thrown at a leaking TDC/Ductmate/flanged joint.
What this covers
A rectangular flanged joint leaks, looks open, is misaligned, has gasket trouble, or fails prep for test.
How to use this playbook
- Check mechanical fit-up first. Sealant is not a substitute for a bad joint.
- Check whether duct ends are square and pulled together evenly.
- Check gasket continuity, corners, missing hardware, loose cleats/bolts, and damaged flange.
- Check if screws/cleats are installed correctly for the joint system.
- Clean surfaces before sealant/tape.
- Use only approved sealant/tape/mastic for the job.
- Ask if the flange is bent, missing gasket, wrong size, or cannot pull square.
Check
- Flange corner
- Gasket line
- Hardware/cleat condition
- Leak point
Warnings
- Do not bury missing gasket under mastic.
- Do not seal over dirty/oily metal.
- Do not overdrive screws and deform the joint.
- Do not cover labels/access/inspection points.
Stop and ask
- Ask when the joint is physically wrong, damaged, missing parts, wrong system, or when sealing method/spec is unclear.