Pipe Size Reference

Flite Sign Co. — Standard Wall vs. Schedule 40

Standard (STD) is not the same as Schedule 40 for NPS 11" and up. They're equal from 2"–10". At 11" and larger, Standard Wall is fixed at .375" regardless of what Schedule 40 says — Schedule 40 keeps getting thicker as pipe gets bigger (e.g. 18" SCH 40 = .562" wall), but "18" standard wall pipe" still means .375". Always read the STD column below when a spec says "Standard" or "STD Wall." Rows/cells where they diverge are flagged in red.

Full Pipe Size Chart

NPS	OD (in)	STD Wall	STD Wt (lb/ft)	STD ID (in)	SCH 40 Wall	X-Heavy Wall	X-Heavy Wt (lb/ft)

Common sign pipe size SCH 40 diverges from STD — use STD for "standard wall" callouts