Natural Gas - Pipe Sizing

Sizing low pressure natural gas pipe lines - imperial units

The tables below can be used for natural gas pipe sizing.

Steel Pipe - Schedule 40

Capacity of Pipe (MBH ≈ CFH)
Pipe Size (in) Pipe Length (ft)
Nominal Inside diameter 10 20 40 80 150 300
1/2 0.622 120 85 60 42 31 22
3/4 0.824 272 192 136 96 70 50
1 1.049 547 387 273 193 141 100
1 1/4 1.380 1200 849 600 424 310 219
1 1/2 1.610 1860 1316 930 658 480 340
2 2.067 3759 2658 1880 1330 971 686
2 1/2 2.469 6169 4362 3084 2189 1593 1126
3 3.068 11225 7938 5613 3969 2898 2049
4 4.026 23479 16602 11740 8301 6062 4287
5 5.047 42945 30367 21473 15183 11088 7841
6 6.065 69671 49265 34836 24632 17989 12720
8 7.981 141832 100290 70916 50145 36621 25895

natural gas pipe capacity diagram

  • pressure less than 1 1/2 psig
  • common to use fittings factor 1.5 - equivalent pipe length in table above = pipe length + 50%
  • pressure drop 0.5 inches water column
  • specific gravity of natural gas 0.6
  • energy content in natural gas 1000 Btu/ft3 (37.26 MJ/m3)
  • steel pipes schedule 40

For natural gas the nominal BTU/ft3 varies from about 900 to 1100 BTU/ft3. In general it is common to set

  • 1 Cubic Foot (ft3, CF) = Approx 1,000 BTUs
  • 1 CFH = 1 MBH

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Copper Tubing - type K

Capacity of Pipe (MBH ≈ CFH)
Pipe Size (in) Pipe Length (ft)
Nominal Outside Diameter Inside Diameter 10 20 40 80
1/4 3/8 0.305 15 10 7 5
3/8 1/2 0.402 33 24 17 12
1/2 5/8 0.527 74 52 37 26
5/8 3/4 0.652 138 97 69 49
3/4 7/8 0.745 203 143 101 72
1 1 1/8 0.995 469 332 235 166
1 1/4 1 3/8 1.245 894 632 447 316
  • pressure less than 1 1/2 psig
  • common to use fittings factor 1.5 - equivalent pipe length in table above = pipe length + 50%
  • pressure drop 0.5 inches water column
  • specific gravity of natural gas 0.6
  • energy content in natural gas 1000 Btu/ft3 (37.26 MJ/m3)
  • One MBH is equivalent to 1000 BTU's per hour
  • copper tubing type K

Copper Tubing - type L

Capacity of Pipe (MBH ≈ CFH)
Pipe Size (in) Pipe Length (ft)
Nominal Outside Diameter Inside Diameter 10 20 40 80
1/4 3/8 0.315 16 11 8 6
3/8 1/2 0.430 41 29 20 14
1/2 5/8 0.545 81 58 41 29
5/8 3/4 0.666 146 103 73 52
3/4 7/8 0.785 236 167 118 84
1 1 1/8 1.025 511 362 256 181
1 1/4 1 3/8 1.265 936 662 468 331
  • pressure less than 1 1/2 psig
  • common to use fittings factor 1.5 - equivalent pipe length in table above = pipe length + 50%
  • pressure drop 0.5 inches water column
  • specific gravity of natural gas 0.6
  • energy content in natural gas 1000 Btu/ft3 (37.26 MJ/m3)
  • One MBH is equivalent to 1000 BTU's per hour
  • copper tubing type L
  • 1 Btu/h = 0.293 W
  • 1 lb = 0.4536 kg
  • 1 ft (foot) = 0.3048 m
  • 1 in water = 248.8 N/m2 (Pa) = 0.0361 lb/in2 (psi) = 25.4 kg/m2 = 0.0739 in mercury
  • 1 psi (lb/in2) = 6,894.8 Pa (N/m2)

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