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Apprentice answer

Why does a metal-to-metal duct connection at a louver sleeve whistle

2nd YearRoof Curbs, Louvers & Exterior AirStandard Correction

Metal-to-metal sleeve joints leak. Pull the flange, clean the faces, add the approved gasket/sealant detail, and re-tighten evenly.

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Plain-English answer

A duct flange bolted to a louver sleeve can look solid but still leak if the gasket is missing. Under fan pressure, the gap becomes a whistle.

Verify the joint face, gasket, fastener spacing, and sleeve alignment. The recovery is to unbolt the joint enough to clean it, install the approved butyl/neoprene gasket or sealant system, then tighten evenly without twisting the sleeve.

Ask Foreman

The duct-to-louver sleeve at [location] is whistling and appears bolted metal-to-metal. Do you want me to open the joint and add the approved gasket/sealant detail?

Verify before acting

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

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