Seamless vs Welded Wall Calculator

See how the ASME B31.3 joint efficiency factor (seamless E=1.00 vs ERW E=0.85) changes the wall thickness you need for the same pressure.

Design pressure (psi) Pipe outside diameter (in) Allowable stress S (psi) — TP304/316 ~16,700 at ambient

Simplified Barlow estimate (t = PD ÷ 2SE); not a substitute for full ASME B31.3 design with corrosion and mill-tolerance allowances.