Flat-oval transition to rectangular

Before you start

• Confirm the flat-oval size, major and minor axis orientation, material, pressure class, joint type, and support detail against the approved drawing.
• Inspect the duct for sidewall dents, flattened ends, twisted axes, damaged beads, split seams, and shipping damage before lifting it.
• Check that the mating pieces use the same oval profile. A round-looking end and a truly matched flat-oval end are not the same thing.
• Stage the correct fittings, joint hardware, approved fasteners, sealant or gasket system, supports, lifting equipment, and hand tools before starting.

Lay it out

1. Confirm which end is flat oval and which is rectangular, along with top, bottom, flat side, and airflow direction.
2. Verify both end dimensions and the fabricated transition length against the field opening.
3. Check the transition taper for clearance to structure, insulation, and access zones.

Set and support it

1. Support the transition body so neither tapered panel carries the full weight.
2. Set the wider or heavier end at the correct elevation first.
3. Provide support near the opposite end so the fitting does not lever on the first connection.

Make the connection

1. 1

   Mark the transition orientation before lifting.

2. 2

   Set and connect the first end using the correct joint system for that shape.

3. 3

   Verify the flat-oval major axis and rectangular top/bottom planes remain correct.

4. 4

   Bring the second run into alignment without twisting the transition.

5. 5

   Complete the second connection using the correct joint system.

6. 6

   Seal both joints after the mechanical connections are complete.

7. 7

   Check the inside path for a step, lip, or field deformation.