How do I test a welded grease duct system for leaks (light test vs. water test)?

The Light Test (Standard Rough-In): Pass an ultra-bright (10,000+ lumen) construction LED light bar slowly through the inside of the completely assembled, uninsulated duct run. A helper walks the dark exterior of the run checking for any pinpricks of light escaping through the welded seams. Any visible light leak indicates a structural weld failure that must be ground down and re-welded.

['The Light Test (Standard Rough-In): Pass an ultra-bright (10,000+ lumen) construction LED light bar slowly through the inside of the completely assembled, uninsulated duct run. A helper walks the dark exterior of the run checking for any pinpricks of light escaping through the welded seams. Any visible light leak indicates a structural weld failure that must be ground down and re-welded.']

Stop if

• Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.

Steps

• Stop and verify the approved detail, manufacturer instructions, foreman direction, and project specs before touching it.
• The Light Test (Standard Rough-In): Pass an ultra-bright (10,000+ lumen) construction LED light bar slowly through the inside of the completely assembled, uninsulated duct run. A...

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