STEAM PROPERTIES & FLOW CHARACTERISTICS
SIZING STEAM PIPES • Steam Velocity Chart (Schedule 40 pipe) Saturated steam lines should be sized for a steam velocity of 4800 to 7200 ft/min.
Piping on pressure reducing stations should be sized for the same steam velocity on both sides of the regulator. This usually results in having a regulator smaller than the piping and having larger piping on the downstream side of the regulator. Example using Steam Velocity Chart: 100 PSIG Inlet Pressure to control valve; 25 PSIG Outlet Pressure; 1,000 lbs/hr flow rate; Determine pipe size required. Upstream Piping: Enter Velocity Chart at A 1000 lbs/hr. Follow line to B 100 PSIG Inlet Pressure. Follow line vertically upwards to C 1 1 / 2 ” Pipe Diameter. Steam Velocity at D shows 4800 ft/min. Downstream Piping: Enter Velocity Chart at A 1000 lbs/hr. Follow line to E 25 PSIG Outlet Pressure. Follow line vertically upwards to F 2 1 / 2 ” Pipe Diameter. Steam Velocity at G shows 5500 ft/min.
20,000
Recommended Steam Velocities
Pipe Size
4,000 5,000 6,000 8,000 12,000 10,000
Process Steam 8,000-12,000 FPM
G
F
Flash Vent Lines 3,000 FPM Heating Systems 4,000-6,000 FPM
C
D
3,000 2,000
1,000
2,000 3,000 4,000 5,000 6,000 8,000 10,000 20,000 30,000 40,000 50,000
Multiply Chart Velocity by Factor below to get Velocity in Schedule 80 Pipe Pipe Size 1/2" 3/4" & 1" 1 1 / 4 " & 1 1 / 2 " 2" to 16" Factor 1.30 1.23" 1.17 1.12 1.23
A
200 300 400 500 600 800 1,000
E
B
Steam Pressure PSIG (Saturated Steam)
100
Note: Condensate Line & Vent Line Size based on using Schedule 40 Pipe
53
Tel: 610-495-5131 • Pottstown PA • USA •• www.watsonmcdaniel.com
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