Why is stretching butyl gasket tape a bad idea?

Field answer

To save time while prepping TDC companion flanges on the ground, you pull and stretch the sticky butyl gasket tape thin to make it reach the corners of a large plenum box, causing it to gap and tear along the metal rim.

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. The likely recovery is to check the condition, correct prep/setup if it is within your assignment, and bring the foreman clean information before the work creates rework overhead.

What to check first

• 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.

Why it matters

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

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Final direction belongs to the foreman, approved drawings/specs, manufacturer instructions, pressure/material schedule, employer policy, and AHJ/code requirements.