Governing equation
ΔP = f × (L/D) × (ρ × v²) / 2. Friction factor f from Colebrook-White or the explicit Swamee-Jain form. Add equivalent lengths for fittings and valves from a K-factor or Le/D table.
Inputs you need
- Fluid density ρ and dynamic viscosity μ at flowing T
- Volumetric or mass flow rate
- Pipe inside diameter D and absolute roughness ε
- Straight length L and fittings inventory
- Elevation change Δz for static head
Output
- Reynolds number and flow regime
- Darcy friction factor f
- Frictional ΔP, static ΔP and total ΔP
- Velocity check vs erosion / noise limits (e.g. API RP 14E)
Limits of use
Single-phase, incompressible or low-Mach compressible flow only. For two-phase, slug, or choked flow use a dedicated method. Treat results as screening — confirm with detailed hydraulics for final line sizing.
Key references
- · Crane TP-410
- · API RP 14E (erosional velocity)
Use of this content
This page is a decision-support and training reference. It is not a substitute for the governing code, the project specification, or the judgement of a responsible engineer. Always validate against the current edition of the applicable standard before use on live engineering work.