Reference: Gas Pipeline Hydraulics, 2005, CRC Press, E. Shashi Menon, Chapter 3, page 127 Example 9


Pipe Flow Expert File: Case_16_Natural_Gas_Pipeline_Pressure_Regulator.pfe


Problem Description: 

A natural gas pipeline with internal diameter 15.5 inches, 50 miles long, with a branch pipe as shown in the screen image below, is used to transport 100 MMSCFD gas from A to B.

At B, 20 miles downstream of A, a delivery of 30 MMSCFD occurs into the branch pipe BE which has internal diameter of 8.125 inches, length 15 miles.  

The delivery pressure at E must be maintained at 300 psi.g.  

The remaining volume of 70 MMSCFD is shipped to the terminus C at a delivery pressure of 600 psi.g.  

The gas is at 60 °F, with a specific gravity of 0.6 and a viscosity of 0.0119 centipoise. 

Compressibility factor is 0.88 and pipeline efficiency is 0.95.


Calculate the inlet pressure required at A.  Is a pressure regulator required at E?

If the inlet flow at A drops to 60 MMSCFD, what is the impact in the branch pipeline BE if the flow rate of 30 MMSCFD is maintained?


The calculation method used for the published data was the Panhandle A equation.


A screen shot of a graph??Description automatically generated


Fluid Data: Natural Gas with specific gravity 0.60 (0.046 lb/ft3), 60 °F, 0.00 kPa.g, viscosity 0.0119 centipoise.

Pipe Data: Absolute roughness 0.001811 inch.

Calculation Method: Panhandle A Isothermal equation, Node Adjust Method.

Standard Atmospheric Model: 60°F, 14.696 psi

Gas Physical Model: Real Gas Model (Ideal Gas Law with compressibility factor Z=0.88).


Result Comparison: 


Data Item

Published data

Pipe Flow Expert

Pipe Flow Expert

Inlet pressure at A (psi.g) for 100 MMSCFD flow

700.38 psi.g

700.74

700.74

Pressure at E (psi.g) (regulator requirement for 100 MMSCFD flow)

530.2 psi.g; Regulator is needed

529.90 psi.g; Regulator is needed to maintain 300 psi.g

Regulate at 300 psi.g PRV Loss calculated is 229.901 psi 

Pressure at B (psi.g) for 60 MMSCFD total flow

609.77 psi.g

609.81

609.81

Pressure at E (psi.g)

(regulator requirement for (60 MMSCFD flow)

486.06 psi.g; 

Regulator is needed

485.57 psi.g; Regulator is needed to maintain 300 psi.g

Regulate at 300 psi.g PRV Loss calculated is 185.57 psi


Commentary: 

The published data and the calculated results compare well.