How do I know if S-and-drive is allowed for this duct?

Do not guess from habit. Whether S-and-drive is acceptable depends on duct size, pressure class, leakage requirements, project specs, shop drawings, and SMACNA/project construction standards.

Verify the required connector type before adapting anything. S-and-drive versus flanged duct is a drawing/spec/shop-standard call, not a habit call.

Rectangular Duct & Fittings 2nd Year YELLOW

Stop if

Ask any time pressure class, duct size, leakage class, or connector callout is unclear.

Watch out

Do not mix connector systems in the field without approval.

Check

Check the piece mark
Check the approved connection detail
Verify both duct ends are meant to connect

Steps

Check the duct schedule/spec if available.
Look at shop drawing notes and connector callouts.
Ask whether this system/size/pressure class uses S-and-drive.
Do not substitute connector systems.
Document if the field material does not match the detail.

Say this to your foreman

In Rectangular Duct Assembly: S-and-Drive, I'm looking at: How do I know if S-and-drive is allowed for this duct? What should I verify before I cut, drill, seal, cover, move, or install?