316 Stainless Ductwork for corrosive environments

1. Pharmaceutical Manufacturing
   

   • Handling airborne solvent vapors, corrosive powders, or fumes.

   • Cleanroom compatibility.

2. Chemical Processing Facilities

   • Extracting or conveying acidic, toxic, or highly reactive gases.

   • Suitable for fume cupboards and reactor extract systems.

3. Laboratories (Biological & Chemical)

   • Ducting for fume hoods with high chemical exposure.

   • Ensures long-term integrity with minimal degradation.

4. Waste Incineration and Wastewater Treatment Plants

   • Corrosive off-gas extraction.

   • Hydrogen sulfide and other aggressive compounds are common.

5. Food Processing Plants (Aggressive Cleaning Agents)

   • Environments where strong chlorinated or acidic cleaners are used.

6. Aerospace or Electronics Facilities

   Where clean, contamination-free exhaust air systems are critical.

   Why It’s Necessary
   

   Corrosion Resistance: 316 includes molybdenum, which significantly improves resistance to chlorides, acids, and industrial solvents.

   Longevity: Stainless systems don’t degrade like galvanized or aluminium under chemical stress.

   Safety: Prevents duct degradation that could leak hazardous fumes into occupied spaces.

   Compliance: Enables installations to meet strict air quality, environmental, and fire safety regulations.

   
   

   DW/144 Guidance Highlights (Relevant to Stainless Steel)

   DW/144 is primarily written for galvanized mild steel, but when using alternative materials like stainless steel, you should:

   1. Material Specification:

      • Declare material in job specs and on drawings. State “316 Stainless Steel to ASTM A240”.

      • Ensure proper gauge for the duct size and pressure class.

   2. Welding & Joints:

      • Seam welding is recommended in corrosive environments.

      • Fully seam-welded ductwork (longitudinal and transverse) prevents corrosion in crevices.

      • Use TIG or laser welding for neat, low-contamination seams.

   3. Testing Requirements:

      • DW/144 recommends pressure/leak testing for high-integrity systems — mandatory if toxic gases are present.

      Consider hydrostatic or dye penetrant testing on welds if it’s safety-critical.

      
      

      Should It Be Fully Seam Welded?

      ✅ Yes, for toxic or aggressive environments.

      Reasoning:

      Seam welding avoids pinholes or gaps where corrosion could start.

      Eliminates reliance on mastic or gaskets, which may degrade under chemical exposure.

      Offers maximum integrity for high-pressure or hazardous airflows.

      Needed for compliance with higher safety standards, e.g. ATEX or hazardous exhaust systems.