TinnerFlow
Grease Duct Systems ยท Grease Exhaust Systems

Stainless grease duct exposed in kitchen

Visible commercial kitchen run

Life-safety system.
The approved design, adopted code, qualified procedure, and exact manufacturer instructions control this installation.
ConnectionContinuous stainless weld or listed stainless system
SupportStainless/compatible supports

Before you start

  • Grease duct is a fire/life-safety system. Verify the approved design, adopted code, hood and fan requirements, listed enclosure or shaft details, and inspection hold points before fabrication or installation.
  • Confirm stainless grade, finish, weld procedure, filler, shielding or purge requirement, support material, dissimilar-metal isolation, and approved finish-restoration method.
  • Review the exposed architectural appearance, seam and joint orientation, support layout, and cleaning requirements.
  • Protect finished stainless from carbon-steel contamination, dirty gloves, grinding dust, and construction damage.
  • Inspect all pieces for scratches, dents, heat tint from prior work, or mismatched finish before lifting.

Tools and materials

Stainless grease-duct sections, stainless-compatible welding equipment and filler, purge equipment when specified, dedicated stainless brushes and abrasives, soft slings, clean gloves, compatible supports and isolation materials, finish-restoration supplies, level or laser, and protective coverings.

Lay it out

  1. Laser the visible route, joint spacing, support rhythm, and bottom elevation.
  2. Mark weld and seam orientation so the exposed run looks consistent.
  3. Keep cleaning access, hood service, and fire-suppression components visually and physically accessible.

Set and support it

  1. Install neat, compatible supports before lifting the finished sections.
  2. Isolate dissimilar metals where the approved detail requires it.
  3. Use soft slings and padded contact surfaces to protect the finish.

Make the connection

  1. 1

    Clean and prepare the stainless mating edges with dedicated tools.

  2. 2

    Set both supported sections and verify visible alignment before tack welding.

  3. 3

    Clamp and tack in a sequence that controls distortion.

  4. 4

    Complete the continuous liquid-tight stainless weld using the qualified procedure.

  5. 5

    Allow cooling, then clean heat tint and restore the finish using the approved method.

  6. 6

    Inspect for contamination, pinholes, distortion, scratches, and visible mismatch.

  7. 7

    Remove protective film and final-clean only when surrounding construction will not damage the surface.

Check the install

  • The exposed run is straight, cleanable, and visually consistent.
  • Welds are continuous, liquid-tight, and finished as specified.
  • No carbon-steel contamination, rust staining, deep scratch, or uncontrolled heat tint remains.
  • Supports are compatible, neat, and do not trap grease or cleaning residue.
  • Access and service components remain usable.

Common mistakes

  • Using carbon-steel brushes, grinding wheels, or contaminated work surfaces on stainless.
  • Finishing one weld differently from the rest of the exposed run.
  • Allowing support hardware to create unapproved dissimilar-metal contact.
  • Removing protective film too early and damaging the final surface.

Stop and ask

Stop if stainless grade, filler, purge, finish-restoration method, dissimilar-metal isolation, or exposed appearance requirement is not approved, or if contamination cannot be removed properly.