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Plant Engineering Calculator

Updated Sep 18, 2026

Steam Header Pressure Drop Calculator — Velocity, Friction & Outlet Pressure

Estimate preliminary steam-header friction pressure drop from mass flow, density, pipe diameter, length and Darcy friction factor, with velocity and outlet-pressure checks.

Live calculationWorking shownPrivate in browser

Inputs

Results

Steam velocity 22.64 m/s
Friction pressure drop 0.154 bar
Outlet pressure 9.846 bar abs
Pressure loss 1.54 %
Velocity diagnostic: Below a common 25–40 m/s saturated-steam planning band; pressure-drop and drainage still require review.
More actions

Shared links reopen these inputs. Recent and saved calculations stay in this browser unless you clear site data.

Formula

v=ṁ/(ρA); ΔP=f(L/D)ρv²/2.

Your calculation, step by step

These steps use the values currently entered above so the result can be checked independently.

  1. 1.Pipe ID = 150.00 mm ÷ 1000 = 0.15000 m; area A = πD²/4 = 0.017671 m².
  2. 2.Velocity v = ṁ/(ρA) = 2.0000 ÷ (5.0000 × 0.017671) = 22.6354 m/s.
  3. 3.Dynamic-pressure term ρv²/2 = 5.0000 × 22.6354² ÷ 2 = 1280.90 Pa.
  4. 4.Darcy drop = 0.01800 × (100.00 ÷ 0.15000) × 1280.90 = 15370.80 Pa = 0.15371 bar.
  5. 5.Outlet screen = 10.0000 − 0.15371 = 9.84629 bar abs (1.537% friction loss).

How to use this calculator

  1. Enter measured or design values using the units shown beside each field.
  2. Review the live results and the substituted calculation steps before using the estimate.
  3. Check the assumptions below, then continue to a related calculator when the next engineering decision needs another model.

Worked example

The calculator exposes velocity alongside Darcy-Weisbach friction so unrealistic high-velocity inputs are visible.

Assumptions and limits

  • Steam density must match the operating pressure/state; this is not an IAPWS solver.
  • Use actual inside diameter, not nominal pipe size, when translating a schedule to the entered ID.
  • Fittings/equivalent length, elevation, condensation and two-phase effects require separate allowances.
  • If calculated friction drop approaches inlet pressure, switch to a compressible steam-sizing method with changing properties rather than extrapolating this constant-density screen.

How to interpret the result

Treat the primary result as an engineering screening value, then use the secondary outputs to understand scale, energy or operating impact. Confirm site measurements, equipment limits and applicable standards before making a design or control change.

Questions engineers ask

Why is steam density an input instead of calculated from pressure?

This screening owner deliberately avoids pretending to be a steam-property solver. Enter density consistent with the actual pressure/state from steam tables or a validated property source; saturated, wet and superheated steam can differ materially.

Why should both velocity and pressure drop be checked?

A steam line can satisfy one criterion and fail the other. Excess velocity raises noise, erosion and water-hammer concerns, while excessive pressure loss can starve downstream equipment. Steam specialists commonly size/check using both methods for longer mains.

What if calculated friction drop approaches or exceeds inlet pressure?

The constant-density Darcy screening model has left its valid range. Do not clamp the outlet pressure to zero and treat that as a result; use a compressible steam-line calculation with changing properties, fittings/equivalent length and the real downstream pressure requirement.

Continue the calculation

Use the next calculator in the same engineering workflow instead of restarting from search.

steam pipe sizingsteam velocitysteam header diversity
Methodology. MAXScanner shows the governing formula, entered values and calculation outputs so the estimate is auditable. The calculator is a screening aid; assumptions and equipment-specific limits remain part of the engineering review.