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Apprentice Q&A · #338

Why did my 45-degree offset travel piece fall short?

2nd YearGREEN · Standard Correction45° Offset Math / Travel Piece

Short answer

A 45° offset travel piece follows the diagonal path, not the flat throw. Use the 45° multiplier, then subtract the fitting takeoffs before cutting the spool.

Field answer

For a basic 45° offset, the straight travel piece is not the same as the flat offset distance. The pipe or duct is moving along the diagonal, so the travel length is longer than the measured throw.

Use the 45° trade multiplier to get the centerline travel, then account for fitting center-to-face dimensions, collars, flanges, and any shop takeoff before cutting metal. The math gets the rough path; the actual fitting dimensions finish the cut.

What to check first

Do not do this

Do not cut the travel spool to the flat offset distance and expect a 45° offset to land correctly.

Why it matters

Bad offset math wastes material, shifts the downstream run, and creates extra rework around obstructions.

Ask foreman

I measured the offset at [measurement], but the first spool was cut to the flat throw and landed short. I recalculated the 45° travel path and fitting takeoffs. Do you want me to recut the travel piece to that layout?

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