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Apprentice Q&A · #093

How do I field-cut a tap into the side of a massive low-pressure trunk line?

2nd YearField ModsYELLOW · Check First

1. Position the raw flange of your starting collar fitting against the trunk wall and trace its outer footprint. 2. Mark a secondary line 1 inch inside that perimeter footprint. 3. Drill a starter hole, cut out the inner circle/square pattern on the interior line, then use your snips to cut tabs out from the hole edge to your original outer footprint line. 4. Fold these internal tabs back out flat, slide the collar in, and sandwich the trunk wall between the tabs and the fitting flange befor

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Plain-English answer

1. Position the raw flange of your starting collar fitting against the trunk wall and trace its outer footprint. 2. Mark a secondary line 1 inch inside that perimeter footprint. 3. Drill a starter hole, cut out the inner circle/square pattern on the interior line, then use your snips to cut tabs out from the hole edge to your original outer footprint line. 4. Fold these internal tabs back out flat, slide the collar in, and sandwich the trunk wall between the tabs and the fitting flange before screwing it down solid.

Field checklist

Ask Foreman

Hey boss, I’m checking field mods: How do I field-cut a tap into the side of a massive low-pressure trunk line? I found the likely issue and want to verify the next step before I lock it in. Do you want me to adjust it now or check the drawing/detail first?

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Verify before acting

Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.

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