Check the velocity in a pipe from the flow rate and size, or work the other way and find the smallest standard pipe that keeps velocity below a limit. The calculator uses actual internal diameters from the ASME B36.10 schedule tables rather than nominal sizes.
What it gives you
- Velocity from flow rate and actual bore
- Cross-section and flow area
- Smallest standard pipe for a target velocity
- Velocity by pipe size table at the current flow
- Typical velocity limits for water, steam and gas services
Method and standards
Velocity is flow rate divided by the internal cross-section. Internal diameters come from the schedule tables so that, for example, a 4 inch Schedule 40 pipe is treated as 102.3 mm bore rather than 100 mm. Recommended velocity limits differ by service; typical values are 1 to 3 m/s for water and 20 to 40 m/s for saturated steam.
How to use it
- Enter the flow rate in your preferred unit.
- Select a pipe size and schedule, or enter a target velocity.
- Read the velocity, or the recommended size, and check it against the service limit.
Questions engineers ask
- Why does it use schedule tables?
- The bore of a given nominal size changes with wall thickness. Using the actual internal diameter avoids a velocity error of several percent.
- What velocity should I design to?
- It depends on the service: erosion, noise, pressure drop and settling all set limits. The tool shows typical ranges, and the pressure loss calculator quantifies the friction consequence.
- Does it calculate pressure drop?
- No. Use the pipe flow and pressure loss calculator for friction and fittings losses.
Need this calculation done properly, with a signed-off calculation pack or FEA behind it? Forgepoint provides mechanical design, analysis and pressure equipment engineering from Manchester, UK-wide.
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