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Taps, Branches & Fittings ยท Taps, Branches & Fittings

Round spin-in with volume damper

Branch off rectangular main

ConnectionSpin-in collar with tabs/screws
SupportIndependent branch support

Before you start

  • Confirm spin-in size, location, damper requirement, handle-access side, airflow direction, and branch route.
  • Check the main for seams, reinforcement, joints, access doors, and nearby taps.
  • Verify the branch will clear the damper handle after insulation and ceiling work.
  • Support the cookie before the final cut.

Tools and materials

Round spin-in with volume damper, layout template, marker, approved cutting tools, hand seamer, clamps, level, approved fasteners, sealant, branch hanger, and deburring tools.

Lay it out

  1. Mark the opening from the approved branch centerline.
  2. Orient the damper handle toward the accessible side.
  3. Keep the opening clear of main-duct seams and reinforcement.

Set and support it

  1. Support the main as needed before cutting.
  2. Set the spin-in in the opening and square the collar from the main-duct reference.
  3. Clamp the flange flat before installing fasteners.
  4. Install the first branch hanger so the branch will not pull on the tap.

Make the connection

  1. 1

    Cut the opening while holding the cookie.

  2. 2

    Remove the cookie and deburr the edge.

  3. 3

    Insert the spin-in and set the collar direction.

  4. 4

    Square the collar to the branch centerline.

  5. 5

    Clamp the flange flush to the main.

  6. 6

    Install approved fasteners evenly around the flange.

  7. 7

    Seal the full spin-in flange.

  8. 8

    Operate the damper and verify handle clearance.

  9. 9

    Connect and support the branch independently.

Check the install

  • The spin-in is square and flush.
  • The damper moves freely and remains accessible.
  • The branch is fully seated and independently supported.
  • The tap flange and branch joint are sealed.
  • The main face is not distorted.

Common mistakes

  • Fastening the spin-in before squaring it.
  • Burying the damper handle.
  • Letting the branch weight pull the collar downward.
  • Dropping the cookie inside the duct.

Stop and ask

Stop if the spin-in is too close to reinforcement or another fitting, the handle will be inaccessible, or the branch cannot meet the collar without side pull.