Pipeline Size and Pressure relation

[10815L]

Hi,
Pipelines are sized based on velocity and velocity is deped on pressure and density, please correct me if i'm wrong. if a pipeline is designed for 4000 barrels/day (4" Dia schedule 40) at 4 barg and if there is requirement for more flow passing by increasing a pressure, is this possible to pass 8000 barrels/day at 30 barg at upstream of control valve but down stream is only atm pressure.
Thanks

 

[micalbrch]

Why do you think that velocity bases upon pressure and density? Velocity depends upon pipe diameter and pump flow. The pump flow can depend upon the pressure (or vice versa) but then the relation is usually higher flow = lower pressure.

 

[Latexman]

I'm confused by the context and choice of flow units. Is this liquid, gas, or two phase flow?

Good luck,
Latexman

 

[zdas04]

Latexman,
I don't think you are the only one confused. The OP seems a bit adrift as well.

10815L,
Changes in density are factors in flow equations, but for liquid flows they are very minor factors (generally not within the accuracy of the flow calculation). In gas flows changes in density are critical.

Let us assume that you are flowing liquids and that the units of bbl/day are meaningful, so 4000 bbl/day is 0.26 ft^3/sec. Area of 4-inch Sched 40 is 0.088 ft^2. Dividing makes velocity 2.94 ft/sec. Going to 8000 bbl/day doubles the velocity to 5.88 ft/sec. Neither of those velocity numbers are much of a concern. You didn't say how long the line was so no one can really assess what the new speed will do to friction loss, but you can be sure that you will lose some amount of pump hp to friction. You need to do that calculation to see if you have enough pump to handle the load.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[10815L]

Hi,
my concern is about the capacity of line, not for velocity. the is study the production separator HAZOP in case normal flow blockage due to esd operating then oil flow will diver to samp tank and samp tank inlet line is only 4'' dia. I want to know about the concerns and openion for this point.
Thanks
10815L

 

[zdas04]

Spoken like a true Pointy-Haired-Boss-In-Training. You want to do Engineering without the details. Well pal, without velocity you don't have any capacity. Any change in liquid-flow capacity in a fixed volume has resulted from a change in velocity. Maybe you should ask your question of an Engineer who is scheduled to be at the HazOp because to me you come across as a lazy jerk that wants the answers without having to bother to understand the question.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[TD2K]

10815L, if obviously your two posts weren't obviously related to each other, I would have guessed they were dealing with two entirely different subjects.

Zdas answered your first question to the best he could based on the limited information you supplied and pointed out without knowing more about the piping system in question that's all he could say about your question. You came back with a comment "my concern is about the capacity of line, not for velocity" but do not supply the missing information Zdas has alreay pointed out is needed to even try to quantify an answer. Please take some time to properly formulate your question and provide the necessary information for us to try and answer it. If you don't know what information is needed, have your process engineer visit the site.

Otherwise your questions are likely to be simply ignored.

 

[10815L]

Dear Sir,
Pointy-Haired boss is very interesting term used (for me), I will try to explain my question again.
we have drain line 4" dia (line is designed based on 1 m/sec velocity for 4000 barrels/day of oil)), now if due to some problem in downstream system and not able to send oil to dehydrator and want to send 8000bbls/day oil tsumpmp tank which is connected with this 4" line. here now pressure is very high (say 28 barg)and not able to reduce this pressure, is this possible to pass that much quantity of oil or not.
I want your opinion,(I know this question relatedted with HAZOP study)what could be consequences of this type of operation.
Thanks
10815L

 

[Latexman]

Do you have an existing drawing or sketch that can be attached? (1000 words)

Good luck,
Latexman

 

[zdas04]

No consequences of putting 8000 bbl/day down the 4-inch unless the friction drop in the line restricts the flow to some lower value. At less than 2 m/s velocity that is unlikely unless the line is several km long.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[Latexman]

If laminar, Q [∝] [Δ]P. 2xQ = 2xP. 4 Barg --> 8 Barg. Source @ 28 Barg. No problem.

If turbulent, Q [∝] [Δ]P^1/2. 2xQ = 4xP. 4 Barg --> 16 Barg. Source @ 28 Barg. No problem.

Good luck,
Latexman

 

[10815L]

Dear sirs,
Thanks for your quick reply and for correction also.
10815L

 

[Latexman]

Of course, this assumes the pipe can handle 28 Barg.

Good luck,
Latexman

 

[786392]

And, Also the "maximum possible shut-off pressure may it be exposed to!!!

Best Regards
Qalander(Chem)