Black iron process exhaust
Industrial exhaust
Before you start
- Confirm process chemistry, temperature, pressure, material thickness, weld procedure, coating or lining system, slope or drainage, structural support, and inspection hold points.
- Determine whether black iron is actually suitable or whether a special alloy or lining is required.
- Inspect sections for rust scale, oil, warped ends, damaged reinforcement, and unapproved field cuts.
- Coordinate hot work, ventilation, fire watch, and nearby process hazards.
Tools and materials
Black iron duct, qualified welding equipment and filler, fit-up clamps, structural supports, reinforcement, level or laser, preparation and cleaning tools, approved coating or lining repair system, PPE, fire blankets, extinguisher, and inspection tools.
Lay it out
- Lay out route, slope, access, support, expansion, and inspection locations.
- Keep full welding access around every joint.
- Coordinate heavy sections and structural loads before lifting.
Set and support it
- Install engineered steel supports and lifting points before closing joints.
- Support both pieces independently and control the section against movement during welding.
- Keep coating or lining surfaces protected until inspection and repair.
Make the connection
- 1
Prepare the mating edges using the qualified procedure.
- 2
Fit and align sections at the planned slope and centerline.
- 3
Clamp and tack in a sequence that controls distortion.
- 4
Complete the continuous weld using the qualified procedure.
- 5
Inspect welds before applying coating or lining.
- 6
Install required reinforcement and structural attachments.
- 7
Restore the specified coating or lining continuously over the completed work.
Check the install
- Welds are complete and inspected.
- Support loads and structural attachments match the design.
- Slope, alignment, and access are maintained.
- Coating or lining continuity is restored after inspection.
- No unapproved material substitution is present.
Common mistakes
- Assuming black iron is suitable for any industrial exhaust.
- Applying coating before weld inspection.
- Welding unsupported heavy sections and loading the joint.
- Failing to restore coating at welds and field cuts.
Stop and ask
Stop if fumes or temperature require an unknown alloy or lining, the weld procedure is absent, structural support is unapproved, or the process hazard is not clearly defined.