PVC-coated galvanized duct
Corrosive exhaust
Before you start
- Confirm the PVC coating type, service chemistry, field-cut method, repair products, fasteners, flange system, support coating, and manufacturer limitations.
- Inspect every section for tears, gouges, bubbles, exposed galvanized edges, and damaged corners.
- Use protected staging and tools that will not scrape or burn the coating.
- Obtain the approved field-repair procedure before cutting or drilling.
Tools and materials
PVC-coated galvanized duct, coated or compatible joint components, manufacturer-approved cutting tools and repair products, compatible fasteners, coated or isolated supports, protective padding, marker, level, and inspection light.
Lay it out
- Plan cuts, penetrations, joints, and supports to minimize coating damage.
- Keep repaired edges and joints accessible for inspection and cure.
- Orient seams and drainage so corrosive liquid does not sit against damaged or repaired coating.
Set and support it
- Use coated or isolated supports with broad contact surfaces.
- Protect the coating at every lift and support point.
- Support both sections before assembling coated flanges or slip joints.
Make the connection
- 1
Inspect and clean the coated mating surfaces.
- 2
Make only approved cuts using the specified method.
- 3
Seal or repair every exposed cut edge before final assembly when required.
- 4
Assemble the coated flange or slip joint without scraping the surfaces.
- 5
Install compatible fasteners and seal all penetrations.
- 6
Repair every coating defect using the approved system.
- 7
Allow required cure and inspect continuity before concealment.
Check the install
- No exposed galvanized edge or bare metal remains.
- Field repairs are continuous and properly cured.
- Fasteners, sealants, and supports are compatible.
- The coating is not crushed or torn at hangers.
- Drainage does not direct corrosive liquid into a damaged edge.
Common mistakes
- Using ordinary snips or abrasive cutting without repairing the exposed edge.
- Covering a tear with generic duct sealant.
- Using uncoated fasteners that become corrosion points.
- Installing a hanger directly over a damaged coating area.
Stop and ask
Stop if coating damage is extensive, the approved field-repair system is unavailable, service chemistry is unknown, or the manufacturer does not permit the proposed field modification.