Please provide a calculation or formula to compare the gas flow in a 4 inch plus 8 inch pipe at 600 psi with the gas flow in a 12 inch pipe at 1000 psi.
Thanks for your assistance,
Ernest
P.S. This is a real-life business situation, not a university exam question

 

Assuming the 4" pipe to be your standard... The 8" will have 4 times the flow and the 12 will have 15 times the flow. I hope this helps.

Kenneth Moore
The Repair Depot

 

Please provide a formula for making thousands of dollars without working.
P.S. This is a real life business situation, not a university exam question.

Seriously, what kind of gas. At what temperature are you planning to flow? What is the super compressibility factor? What type of meter are you using? Orifice? Ultrasonic? ...

Try the American Gas Association and their AGA3 calculations.

 

Thanks for your clear answer, much appreciated.

Ernest

 

Hi Kenneth,
Thanks for your answer, it's a great help. Please post the calculation or formula that you used so that I can use it for futher gas flow problems.
We really appreciate your assistance, Ernest

 

I'm sure a few others will ask to to please explain exactly what you mean ...

Assuming you are looking at two alternative situations -

volumetric flow is proportional to the product of area and velocity. A 12" line has a cross-section which is 1.8 x that of the combined 4" and 8" lines. So for the same velocity the volumetric flow in the 12" line will be 1.8 x that in the two smaller lines combined.

Mass flow depends on density and this in turn is proportional to absolute pressure. Since your pressures are so high, you can ignore the difference between absolute and gauge, and work with gauge values. In your case, the density at 1000 psi is 1.66 x that at 600 psi.

So for the same flowing velocity in each case, you will have 1.8 x 1.666 = 3 x the amount of gas (expressed in mass terms or in standard or normal m^3) in the 12" line.

Hope that helps - and to satisfy my curiosity please explain a bit more about the situation.

Cheers,

Bruce.

 

You may derive the Polyfolw formula:-

T=P.D/2(S.E+P.Y) whereby T=Nominal design thickness

P=Design pressure;D=Pipe Outer diameter;
S=Yield strenght;E=Quality factor;Y=Design coefficient

Then to determine the design thickness;
Tm=T-Tc whereby Tc=Corrosion allowance=1.00

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