Why do large TDC/TDF joints need center flange clips?

Field answer

You are snapping TDF center metal clips onto a completed horizontal trunk line joint on the ground, but you space them 3 feet apart to save clips, causing the metal flanges to bow out in the middle.

Large flat flange spans can bow away from the gasket. Add the required clips per shop standard/project detail so the center span seals, not just the corners. 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

• Check if the flange face bows between corners.
• Confirm required clip type and spacing with shop/project detail.
• Add clips evenly along the flat span.
• Inspect gasket compression after clips are installed.
• Leak-check or listen for whistle at startup.

Why it matters

Center-span flange leaks are common when clips are missing or spaced too far apart.

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