Reference: Gas Pipeline Hydraulics, 2005, CRC Press, E. Shashi Menon Chapter 3, page 94 Example 2a


Pipe Flow Expert File: Case_08_Multiple_Take-offs_Pressure.pfe


Problem Description: 

A 150 mile pipeline carrying methane consists of several injections and deliveries.  

The pipe internal diameter is 19 inches and at point A has an inlet volume of 250 MMSCFD.  

At point B (20 miles downstream of the inlet) 50 MMSCFD is delivered and at point C (80 miles downstream of the inlet) 70 MMSCFD is delivered.  

At point D, 100 miles downstream of the inlet, gas enters the pipeline at 60 MMSCFD.  

Point E represents the end of the pipeline, 150 miles downstream of the inlet.  

Calculate the pressures at points A, B, C and D for a minimum delivery pressure of 300 psi.g at point E. 

Use a drag factor of 0.96 and a compressibility factor of 0.85 throughout.


The calculation method used for the published data was the American Gas Association (AGA) equation.



Pipe Flow Expert Parameters:


Fluid Data: Gas with gravity 0.65 (0.04964 lb/ft3), 60 °F at 0.00 psi.g, viscosity 0.0119 centipoise.

Pipe Data: Roughness 150 micro-inches.

Calculation Method: AGA Isothermal Flow equation with 0.96 drag factor, Node Adjust Method.

Standard Atmospheric Model: 60°F, 14.696 psi.

Gas Physical Model: Real Gas Model (Ideal Gas Law with custom compressibility factor Z=0.85).


Result Comparison: 


Data Item

Published data

Pipe Flow Expert

Inlet pressure A (psi.g)

927.34

924.18

Outlet pressure B (psi.g)

832.25

832.58

Outlet pressure C (psi.g)

610.36

612.59

Outlet pressure D (psi.g)

572.41

572.52


Commentary: 

The published data and the calculated results compare well.  


The calculations used for the published results used an approximation by re-using the AGA transmission factor from the first pipe section (D – E) for all of the other pipe sections, whereas Pipe Flow Expert calculated the AGA transmission factor separately for each pipe section (which is more accurate).