TinnerFlow
Transitions & Reducers ยท Transitions & Reducers

Round concentric reducer

Centered reduction

ConnectionSlip/gasketed
SupportAdjacent supports

Before you start

  • Confirm the large and small diameters, reducer direction, airflow direction, joint type, and support arrangement.
  • Inspect both ends for roundness, damaged beads, gasket condition, and dents.
  • Verify the reducer is not being installed backward.
  • Stage supports on both adjoining runs.

Tools and materials

Round concentric reducer, approved slip or gasketed components, fasteners, sealant, crimper if required, level, tape, marker, bands or saddles, and hand tools.

Lay it out

  1. Mark the large and small centerlines.
  2. Confirm the reducer is concentric.
  3. Plan supports close enough that neither run hangs from the reducer.

Set and support it

  1. Support both adjoining round runs.
  2. Hold the reducer centered.
  3. Prevent rotation during fit-up.

Make the connection

  1. 1

    Seat the large end fully.

  2. 2

    Align the reducer centerline.

  3. 3

    Bring the small duct to the small end without side pull.

  4. 4

    Seat the small connection fully.

  5. 5

    Install approved fasteners evenly.

  6. 6

    Seal required joints.

  7. 7

    Load supports and inspect the reducer for dents or roll.

Check the install

  • The reducer stays concentric.
  • Both ends remain round.
  • Both joints have full insertion.
  • No dent or crimp damage narrows the opening.
  • Neither adjoining run loads the fitting.

Common mistakes

  • Installing the reducer backward.
  • Overcrimping the small duct.
  • Using fasteners to pull a side-loaded joint together.
  • Leaving the reducer unsupported between two runs.

Stop and ask

Stop if the reducer direction, diameters, insertion, or concentric alignment differs from the approved design.