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Steam Pipes - Pressure Drop vs. Steam Flow

Steam pipes and pressure drop diagrams - imperial and metric units.

Pressure drop in steam pipes can be estimated with the diagrams below.

Imperial Units

Steam pipe - pressure drop diagram - imperial units (psi)

The diagram is made for steam with pressure 100 psi schedule 40 steel pipe. For other pressures - use correction factors:

Steam - Steel Pipe Sch. 40 Correction Factor vs. Pressure 100 psi
Pressure (psi) 0 5 10 30 60 90 100 110 150 200 250 300
Factor 6.9 5.2 4.3 2.4 1.5 1.1 1.0 0.92 0.70 0.55 0.45 0.38
  • 1 lbs/hr = 1.26×10-4 kg/s
  • 1 psi (lb/in2) = 6,894.8 Pa (N/m2) = 6.895×10-3 N/mm2 = 6.895×10-2 bar = 27.71 in H2O at 61 oF (16.7 oC) = 703.1 mm H2O at 61 oF (16.7 oC) = 2.0416 in mercury at 61 oF (16.7 oC) = 51.8 mm mercury at 61 oF (16.7 oC) = 703.6 kg/m2 = 0.06895 atm = 2.307 Ft. H2O

Metric Units

Steam pipe - pressure drop diagram in metric units (bar)

The diagram is made for steam with pressure 7 bar. For other pressures - multiply the pressure drop with correction factors:

Steam - Steel Pipe Sch. 40 Correction Factor vs. Pressure 7 bar
Pressure (bar) 0 1 2 4 5 6 7 8.5 10 12 14 20
Factor 6.9 3.67 2.51 1.55 1.31 1.13 1.0 0.85 0.74 0.63 0.55 0.39
  • 1 kg/h = 2.778×10-4 kg/s = 3.67×10-2 lb/min
  • 1 bar = 105 Pa (N/m2) = 0.1 N/mm2 = 10,197 kp/m2 = 10.20 m H2O = 0.9869 atm = 14.50 psi (lbf/in2) = 106 dyn/cm2 = 750 mmHg
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