Work out steam pipe sizing instantly with clear inputs, formula shown and shareable results.
Steam mains are sized on velocity. Mass flow is converted to volume using the specific volume of saturated steam, approximated here as 446 divided by absolute pressure, then divided by the design velocity to get the bore. Saturated steam distribution normally runs 4,000 to 6,000 fpm; wet steam must be kept slower to avoid erosion.
Volumetric flow
ft³/min = lb/h x specific volume / 60, specific volume ≈ 446 / absolute psia
Bore
Area = flow / velocity; diameter in = sqrt(4 x area / pi) x 12
Preliminary estimate only. Confirm against steam tables and the applicable pressure piping code before fabrication.
ft³/min = lb/h x specific volume / 60, specific volume ≈ 446 / absolute psia. Steam mains are sized on velocity.
Specific volume falls roughly in inverse proportion to absolute pressure, so the same mass of steam occupies far less space and needs less bore at high pressure.
This calculator takes 3 inputs: Steam flow, Steam pressure, Design steam velocity. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.