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Apprentice answer

How much collar engagement does a spiral fitting need

2nd YearRound, Spiral & Flat Oval DuctCheck first

If the collar engagement is too short to hold, do not trust the joint. Replace the fitting or add an approved coupling/detail with proper overlap.

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Plain-English answer

A spiral joint needs enough overlap to fasten and seal. If the pipe only catches a tiny bite of collar, vibration and pressure can walk it apart.

Check insertion depth, collar condition, pipe cut, and fitting type. Recovery is usually a proper long-collar fitting, approved sleeve/coupling, or replacement fitting before final seal.

Ask Foreman

The spiral elbow at [location] has a short collar and the pipe is barely engaged. I stopped sealing it. Do you want the fitting swapped or an approved coupling used for proper overlap?

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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