| S.No. | Checkpoint | IS Requirement | Status |
|---|---|---|---|
| A. DUCT MATERIAL AND SPECIFICATION | |||
| A1 | Duct material specification verified (GI, SS, aluminum) with thickness and manufacturing standard Acceptance: GI duct: ≥0.5 mm thickness (18 gauge); SS: ≥0.4 mm; mill certificates available; no corrosion or damage visible | Cl. 4.1 — Material specification | OK NC NA HOLD |
| A2 | Duct dimensions and size verified against design drawings (length, width/diameter, aspect ratio) Acceptance: Duct dimensions measured and compared with design; tolerance ±5 mm for small ducts, ±10 mm for large ducts | Cl. 4.2 — Dimensional verification | OK NC NA HOLD |
| A3 | Fabrication quality: seams straight, no dents, distortions, or leaks visible (visual inspection) Acceptance: Seams tight and uniform; dent depth < 5 mm if present; no sharp edges or protrusions inside duct; no visible light through seams | Cl. 4.3 — Workmanship quality | OK NC NA HOLD |
| B. DUCT ROUTING AND ALIGNMENT | |||
| B1 | Duct routing per design drawings: no unplanned bends, offsets, or route deviations without approval Acceptance: Duct path follows approved layout; any deviations documented and re-approved; no interference with structure or services | Cl. 5.1 — Route compliance | OK NC NA HOLD |
| B2 | Duct slope and gradient (for gravity drain ducts): minimum slope 1:100 toward drain point verified Acceptance: Condensation drain slope ≥1:100 (1% minimum); measured and confirmed; no low points where water can accumulate | Cl. 5.2 — Drainage gradient | OK NC NA HOLD |
| B3 | Duct alignment: centerline deviation from vertical/horizontal not exceeding 10 mm per 3 m length Acceptance: Plumb/level checked using spirit level or laser; straightness verified; no sagging or bowing observed | Cl. 5.3 — Alignment tolerance | OK NC NA HOLD |
| B4 | Duct turns and bends: radius of turns ≥ 1.5 × duct width (for rectangular) or 1.5 × diameter (for circular) Acceptance: Bend radius measured; complies with minimum; radius < 1.5× requires turning vanes (inspect if installed) | Cl. 5.4 — Turn radius requirement | OK NC NA HOLD |
| C. DUCT SUPPORT AND SECURING | |||
| C1 | Duct supported at appropriate intervals: ≤1.5 m for horizontal ducts, ≤2 m for vertical risers Acceptance: Support spacing measured; ≤1.5 m for horizontal, ≤2 m for vertical; no sagging between supports; load-bearing capacity adequate | Cl. 6.1 — Support spacing | OK NC NA HOLD |
| C2 | Hangers/brackets securely attached to structure and duct; no loose bolts or welds Acceptance: All bolts tight (torque check if critical); welds inspected visually (no cracks); brackets in good condition with no corrosion | Cl. 6.2 — Hanger security | OK NC NA HOLD |
| C3 | Vibration isolation (if required): vibration dampers or resilient mounts installed under ductwork near equipment Acceptance: Dampers installed where specified; resilience verified (deflection < 2 mm under gravity load); mounting torque adequate | Cl. 6.3 — Vibration isolation | OK NC NA HOLD |