13 replies to this topic

[eastorca]

Hi everybody
Refer API 14E I got the equation:
Vl = 0.012*Ql/di^2
Vl = average liquid flow velocity, feet/sec
Q1 = liquid flow rate, barrells/day
di = pipe inside diameter, inches

My question is: following the equation "barrels" means "barrels US" or "barrel UK"?
I also wonder how to convert MMSCFD to ft3/hr?
Thank you

Edited by eastorca, 10 September 2010 - 04:18 AM.

[Zauberberg]

Where did you get the "UK barrel" from? API is an American organization and there is only one Barrel unit used, equivalent to 158.987 liters.

MMSCFD stands for Million standard cubic feet per day. If you want to convert to cubic feet per hour, multiply the MMSCFD figure with 1,000,000 and then divide by 24 (hrs/day) to get the result. If you need actual ft3/hr, you need to know both actual and standards conditions to which the input data correspond to, including gas compressibility factor at both conditions.

[eastorca]

Thank Zauberberg very much

[breizh]

Hi ,
There is a wonderfull tool available on internet : Uconeer .
I will continue to advise people to dowload it.
Breizh

[kkala]

...Refer API 14E I got the equation:
Vl = 0.012*Ql/di^2 Vl = average liquid flow velocity, feet/sec Q1 = liquid flow rate, barrels/day
di = pipe inside diameter, inches
My question is: following the equation "barrels" means "barrels US" or "barrel UK"?
I also wonder how to convert MMSCFD to ft3/hr?

Long time has passed since when this thread has appeared, yet following may be worth while noting:
Reported equation is nothing more than an expression of liquid velocity in non consistent units; we can check what mentioned barrels / day is equivalent to through unit conversions.
Equation can be written as Ql=Vl*di^2/0.012. Arbitrarily assuming e.g. Vl=3 ft/s and di=4.026 in, it gives the result Ql=4052.17 barrels/d, or 168.84 barrels/h.
On the other hand we know that Ql=Vl*(π*di^2)/4, giving Ql=458,29 in3/s (for V1=3*12 in/s and di=4.026 in), that is Ql=1649842 in3/h.
Consequently 168.84 barrels/h = 1649842 in3/h that is 1 barrel = 9771.6 in3, according to the equation given.
But 1 US barrel (bbl) equals 42 US gal, or 42*231 in3 = 9702 in3. So the equation refers to US barrels, as expected. The small difference is due to rounding.
As wikipedia indicates, there is no other "barrel" today for the oil industry.

[Narnia]

Dear All,

For pipe lines design,i need the recommended velocity limits and pressure drop limits for liquid and steamlines, if anybody have kindly send me

thanks

[breizh]

Narnai ,
Let you consider this standard , it should support your query .

Breizh

[ankur2061]

Narnia,

A long time back 'Art Montemayor' one of the administrators had posted an excel sheet with the title "Recommended Fluid Velocities". I was trying to search for the post wherein this excel file was attached through the search function of the forum but was unable to find it.

However, since I have the excel file I am re-attaching it.

Regards,
Ankur.

Attached Files

•  Recommended_Fluid_Velocities.xls   26.5KB   1622 downloads

Edited by ankur2061, 06 October 2011 - 06:10 AM.

[kkala]

Further to recent posts, attached you may find "LS.xls", a selection of recommended velocities and frictional pressure drop per unit length (generally I use them). Allowable velocity can increase with pipe diameter in some cases, as you can see.
Of course these cannot cover all cases, in some of them detailed hydraulic calculations are needed to see e.g. sufficiency of NPSHa, or whether an existing pump is adequate.

Attached Files

•  LS.xls   22.5KB   1187 downloads

[shin29]

We have the case that liquid is flowing in 6" line and pipe line size is 2" for 2 meter length and with bends . IN this 2" line velocity is about 20 m/sec .

How can i study the effect of such high flow on pipeline , adjoining pipeline fittings , structure and the system whole .

I want to equip my argument with more and more resoning and standard guidelines and not on thumb rule or general practices .

Please suggest me some literature and give your valuable suggeltions.

If it is Okay or if not how-come ?

Regards,

sahil

[kkala]

Section of 6" pipe is about 8.6 times more than this of 2" pipe (assumed sch40), so velocity increases from 2.3 m/s to 20 m/s (approximately). Frictional pressure drop ΔPf in this 2 m section will be about 8.6² = 74 times higher for 2" size in comparizon to 6" size. Increase in pumping power (proportional to ΔPf) can be estimated and would not justify smaller investment of 2" pipe section.
Nevertheless it seems you are obliged to use 2" piping for a length of 2 m. There are cases here, where pipe size has to be reduced, e.g. when there is limited space in the pipe rack. The 6" pipe can be also divided into tow pipes of 4" pipe (total section almost same) for the 2 m length. But I think reduction from 6" to single 2" pipe would be too radical here. Another solution would be found.
Below are data concerning "reasoning and standard guidelines" for the above, additional info from others is welcomed.
1. Norsok standard P-001, <http://www.standard....134/p-001e5.pdf>, Chapter 6, Line sizing criteria, Sizing of liquid lines, Velocity limitations. Max liquid velocity 6 m/s for carbon steel pipes, 10 m/s for intermittent service (*).
Note in the standard: The velocities shall be in general be kept low enough to prevent problems with erosion, water-hammer pressure surges, noise, vibration and reaction forces.
2. Preventing mentioned piping problems is usually not responsibility of Chemical Engineer, having to use brief guidelines or rules of thump to be in the ballpark. Water-hammer may be an exception, estimated by many branches of Engineering.
-Vibrations and reaction forces have been met only in books of advanced hydraulics, probably not on a practical basis.
3. You need specific answers and a piping engineer seems most suitable to address the query and advice on pipe supports. Some members have piping design knowledge, and can hopefully give some help.

(*) Known practices recommend lower velocities (see post no 9)

Edited by kkala, 14 March 2013 - 04:40 AM.

[Ajay S. Satpute]

Dear Sahil,

 

Is it possible for you to provide more details of your problem (e.g. P&ID, pump curve, piping data etc.)?

 

Do you have PIPENET to simulate your system?

 

Regards.

 

Ajay

[shin29]

Dear Ajay,

I do not have pipe net , i am attaching here an excel sheet for your referance.

 

regards, 

sahil

Attached Files

•  line section.xlsx   10.65KB   507 downloads

[Ajay S. Satpute]

Dear Sahil,

 

1. Please refer post # 8 of below thread. This may provide some basis for selecting a particular velocity, which shall minimize the erosion wear.

http://www.cheresour...pes/#entry71096

 

2. Surge pressure analysis of your system may suggest to increase pipe size as one the recommendations to minimize the pressure surge (occured due to say, sudden closure of downstream valve).

 

3. In your case, the velocity itself is very high as compared to recommended velocities as per different standards. Please refer below link to get line sizing criteria as per different standards.

http://www.cheresour...velocity-check/

 

4. You also need to consider pressure drop criteria along with the velocity criteria.

 

5. Please refer post # 11 of this thread which tells how we choose line size as consultants. Follow Vmax and max. pressure drop criteria (for liquid) and you are sure that you have designed the system well. But to calculate Vmax using the theoretical formulae would be a good project, but my clients in this part of the world at least won't buy it and would ask for the international standards.

 

Regards.

 

Ajay