Static field route #19640

What do I do when butyl gasket tape was stretched thin on a TDC/Ductmate flange?

Sealing, Leakage, Mastic & Pressure Testing⚠️ CHECK FIRSTField answer expansion

📖 Verified core answer

Butyl gasket needs its thickness to compress and seal. Lay it relaxed, keep it continuous through corners, and remake stretched or torn sections before the joint is bolted shut.

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Field verification checklist

Look for thin, shiny, stretched, or torn gasket sections.
Check corners and end overlaps first.
Remove bad tape instead of burying it under more sealer.
Lay new tape relaxed in the flange track.
Confirm the gasket is continuous before the lift.

Ask foreman

Don't pull or stretch that butyl tape thin just to make it fit the rim. Lay it down relaxed so it keeps its full density, otherwise that high-pressure joint is going to whistle like a train during startup.

Text to foreman

Route options

A Correct prep/setup only if the fix is within your assignment and the approved method is clear.

B Hold and document if it affects safety, structural support, rated assemblies, airflow, access, tools, material condition, or another trade.

C Bring the journeyman/foreman the location, what you checked, and what decision you need before the crew loses time.

Do not do this

Do not stretch gasket tape to make it reach; that steals the compression that seals the joint.

Why this matters

A thin or torn gasket can whistle and leak after startup, especially on larger or higher-pressure joints.

Final verification

Use this as field training guidance. Final direction still comes from the foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, pressure/material schedule, and AHJ/code requirements.

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