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Apprentice answer

Why are loop hangers buckling round spiral duct

2nd YearRound, Spiral & Flat Oval DuctCheck first

Teardrop loops may not control large round duct under dynamic load. Upgrade to an approved rigid saddle, split ring, or trapeze cradle.

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Plain-English answer

A loose strap loop can support dead weight but still let the pipe kick, dimple, or twist when fan pressure changes.

Inspect the barrel where the strap bears. If the wall is dimpling, unload the run and change the support method so the load spreads around the pipe instead of cutting or squeezing one strip.

Ask Foreman

The spiral pipe at [location] is dimpling inside the teardrop loops when the fan runs. I checked the support contact points. Do you want rigid saddles or trapeze cradles installed?

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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