Size, Pressure & Special Routing · Size, Pressure & Special Routing
Medium 8–14 inch spiral branch
Typical commercial branch
ConnectionSlip/gasketed
SupportBand/cable
Before you start
- Confirm 8–14 inch diameter, route, fittings, joint type, hanger spacing, damper access, and branch destination.
- Inspect spiral seams, ends, gaskets, and fittings.
- Check for an unplanned offset before assembly.
- Stage the run in installation order.
Tools and materials
Medium spiral duct and fittings, approved couplings or gasketed joints, fasteners, sealant, bands or cable supports, level, marker, tape, and hand tools.
Lay it out
- Mark centerline and hanger points.
- Coordinate fittings and dampers.
- Keep supports clear of joints.
Set and support it
- Install supports before assembling long sections.
- Support fittings independently where needed.
- Keep the run from rolling.
Make the connection
- 1
Set the first section to line and elevation.
- 2
Seat the next section fully.
- 3
Install approved fasteners and seal.
- 4
Add fittings in the marked orientation.
- 5
Load supports and recheck level.
- 6
Verify damper and service access.
Check the install
- The run stays round and level.
- Joints are complete.
- Fittings are supported.
- No unplanned spring tension remains.
- Access stays usable.
Common mistakes
- Adding a field offset without measuring.
- Supporting at the joint.
- Rolling the spiral seam randomly.
- Leaving fittings to hang from straight pipe.
Stop and ask
Stop for a damaged end, unplanned offset, wrong fitting, or support layout that does not match the route.