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Dampers, Penetrations & Life Safety · Dampers & Life Safety

Access door in rectangular duct

Inspection/cleaning point

ConnectionGasketed access door
SupportLocal reinforcement as required

Before you start

  • Confirm access-door size, pressure and temperature rating, opening location, reinforcement, gasket, latch direction, and service clearance.
  • Check the duct for seams, joints, stiffeners, tie rods, internal liner, and nearby hangers.
  • Verify the door can open or be removed after ceilings and equipment are installed.
  • Support the duct locally before cutting.

Tools and materials

Approved rectangular access door, template, cutting tools, reinforcement where required, fasteners, gasket, sealant, level, marker, deburring tools, and interior-cleaning supplies.

Lay it out

  1. Mark the opening on the reachable side.
  2. Keep the cut clear of reinforcement and transverse joints.
  3. Verify the door swing or removal path.

Set and support it

  1. Support the duct locally.
  2. Add only the reinforcement shown by the approved door detail.
  3. Keep the frame flat during installation.

Make the connection

  1. 1

    Verify the template and cut size.

  2. 2

    Cut the opening while controlling the cookie.

  3. 3

    Deburr and clean the inside.

  4. 4

    Install reinforcement where required.

  5. 5

    Set and fasten the access-door frame.

  6. 6

    Install gasket, cover, and latches.

  7. 7

    Open and close the door and inspect the seal.

Check the install

  • The door opens fully.
  • The gasket seats evenly.
  • Latches secure the cover.
  • No sharp edge or debris remains.
  • The duct remains reinforced and undistorted.

Common mistakes

  • Cutting through reinforcement.
  • Facing the door toward a wall.
  • Leaving metal debris inside.
  • Using a door not rated for the system.

Stop and ask

Stop if the opening cuts reinforcement, the door will become inaccessible, or the selected door does not match the pressure, temperature, or service.