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INPUT   DATA

Title

Inlet pressure		psia
Outlet pressure		psia
Pressure, std. condition		psia
Temperature, std. condition		° F
Mean temperature of line		° F
Inside diameter		inches
Pipe length		miles
Gas relative density
Mean gas compressibility
Pipeline efficiency

Optional Data

Pipe effective roughness		10-6inch
Mean gas viscosity		cp

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OUTPUT   VARIABLES   &   GRAPHS

Gas Flow Equation	Flowrate SCF/day	Computed Friction factor
♦  Weymouth
♦  Panhandle A
♦  Panhandle B
♦  AGA
♦  Ohirhian

Flow Of Compressible Gas In A Horizontal Pipeline

The four commonly-used equations for long-distance gas pipeline are:

Another equation was recently derived by Ohirhian via the manipulation of three basic equations : Weymouth, Colebrook and Reynold's number.

Each of the above five gasflow equations is based on some assumed expression for Friction factor ƒ , a dimensionless correlating function. ƒ_m is the friction factor (also called the Moody friction factor) that is commonly tabulated in the Moody Charts. Quite often the Fanning Friction factor ƒ_f is used: ƒ_f = ƒ_m/4.

The equations for each method is given below:

 -  Panhandle A:

 -  Panhandle B:

 -  AGA (fully turbulent):

 -  Ohirhian:

Where:

   q_sc = gas rate at standard condition, scf/d
   P₁ = inlet pressure, psia
   P₂ = outlet pressure, psia
   P_sc = pressure at standard condition, psia
   T_sc = temperature at standard condition, °R
   T_m = mean temperature of line, °R
   T_g = ground temperature, °R
   μ = mean gas viscosity, cp
   γ = mean gas relative density (air = 1)
   Z_m= mean gas compressibility factor

   d = inside diameter of pipe, inches
   L = pipe length, miles
   E = pipeline efficiency
  ƒ_m = Moody friction factor
  ƒ_f = Fanning friction factor
  F_t = transmission factor (√[1/ƒ_f ])
  ε = absolute roughness of pipe, inches

The mean values of the gas properties (Z & μ) are determined at the average pressure and temperature, derived as follows:

BIBLIOGRAPHY

• Maddox R.N. & Lilly L.L.; Gas Conditioning & Processing, Volumes 2 & 3; Campbell Petroleum Series, Norman, Oklahoma, 1990.
• Katz D.L. & Lee R.L.; Natural Gas Engineering - Production & Storage; McGraw-Hill Publ. Co., New York, 1990, chap. 6.
• Ohirhian P.U.; Direct calculation of the gas volumetric flow rate in horizontal and inclined pipes; Paper SPE-37394, Soc. of Petroleum Eng., Richardson, Texas, 2002.