Material: Galvanized Iron (GI) sheet confirming to IS:277 or Stainless Steel Grade 304 for kitchen/clean areas.
Sheet Thickness: As per SMACNA / IS standards — e.g., up to 750 mm width: 24 G; 751–1500 mm: 22 G; 1501–2250 mm: 20 G; >2250 mm: 18 G.
Construction: Factory-fabricated ducts with lock-form / Pittsburgh seams; joints flanged using TDF/TDC or angle-iron frames.
Supports: GI/MS angle supports spaced ≤ 2.4 m horizontally, with vibration isolation where required.
Sealant: Duct joints sealed with non-hardening mastic or neoprene gasket to ensure air-tightness up to SMACNA Class B or higher.
Insulation: External thermal insulation (e.g., Nitrile Rubber / Glass Wool) and acoustic lining as per design.
Accessories: Access doors, turning vanes, splitter dampers, volume control dampers, and fire dampers as per drawing/spec.
Testing: Ducts tested for leakage and pressure drop as per SMACNA / IS 655 standards before commissioning.
Finish: Internal surfaces smooth and clean; external painted or protected with anti-corrosive primer where exposed.
Installation: Ducts installed true to alignment; cross joints sealed; supports from structure (not ceiling panels); proper coordination with other services.
