Flat-oval vertical riser

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.
• Confirm the riser support, floor frame, guides, shaft clearances, penetration details, and load-transfer points before rigging.

Lay it out

1. Establish a continuous plumb line through the shaft or floor openings.
2. Mark the major-axis orientation at every level so the riser does not rotate between floors.
3. Verify opening dimensions, sleeve or firestop clearance, and access for joint assembly.

Set and support it

1. Set the lower section on the designed riser support before bringing in the next piece.
2. Rig the upper section from approved lifting points and control it against rotation.
3. Use guides or temporary restraint so the narrow sides are not crushed against the shaft opening.

Make the connection

1. 1

   Confirm the lower section is plumb, supported, and oriented correctly.

2. 2

   Lower or raise the next section into alignment while keeping the major axes matched.

3. 3

   Bring the mating profiles together without using the joint to carry the section weight.

4. 4

   Complete the approved joint and fastener pattern.

5. 5

   Apply the required gasket or seal treatment.

6. 6

   Transfer the new section load to the designed support.

7. 7

   Install or verify lateral guides before releasing the rigging.