Pressure Drop Formula
Pressure Drop Formula
(OP)
Dear All,
Is there anybody knows that pressure drop formula(largely used) for oil/petroleum as liquid in pipeline?
thanks.
Is there anybody knows that pressure drop formula(largely used) for oil/petroleum as liquid in pipeline?
thanks.





RE: Pressure Drop Formula
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
For oil & gas - single or 2-phase - I suggest you purchase API Recommended Practice 14E, "Recommend practice for Design and Installation of Offshore Production Platform Piping Systems". Don't let the phrase "Offshore Production Platform" throw you; it works for both shore and offshore. It's simple, direct, and straightforward. I've developed gathering and production line sizing spreadsheets using this and Serghides' equation and they work very well and very accurately.
For long distance pipeline work and single-phase liquids, then I use Darcy's equation and also Serghides. When you get involved in fluid flow and resistance, be sure you own and dominate all that is written between both orange covers of Crane's Tech Paper No. 410. If you don't, you're in for a lot of Excedrin Headaches.
RE: Pressure Drop Formula
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RE: Pressure Drop Formula
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
Excellent advice, BigIncher. No serious engineer should accept a "calculator" result on the internet without thoroughly checking it out and demanding credible and acceptable documentation as references.
Allow me to give you an example (this is meant for all younger engineers who may think they are getting something for nothing) of what happens when you go to sites such as the one mentioned. It just so happens that I've been there and done that and the following was an email that has gone unanswered for exactly one year to date (isn't that a coincidence?):
"To: webmaster@engineeringpage.com
From: artmontemayor37@hotsheet.com
Subject: Your Fluid Flow Calculation Webpage
Date: Oct 31, 2005; 5:08 PM
Sirs:
I visited your webpage after finding out about in one of the Engineering Forums. I like the way you've organized the method of resolving a piping system's pressure drop calculation. I also admire the way you've presented the results.
You say you use the Hooper 2-K calculation method and this provoked me to test your algorithm. I found something wrong in the results when I tried to find the pressure drop for 1,000 gpm of water flowing in 500 feet of 10", sch 40 pipe at a density of 62.5 lb/ft3.
Your results show a pressure drop of 3.54 psi for the straight pipe while I consistently get 1 to 1.25 psi with 5 other programs and this checks with the Hydraulic Institute's pipe tables for clean water.
I consider the 3.5 psi as a very high figure and wonder if others have noted this to you as well. I believe I'm correct and would like to verify this with you since I consider your product as very well organized. There may be a bug in your equations or algorithm and perhaps you can share this possibility with me.
Thank you for your attention to this. I'm an experienced, registered engineer with 45 years of field experience and I'm at a loss to explain the difference.
Art Montemayor
Spring, TX"
I'm still waiting for a response. Great webpages with beautiful colors and great artistic splendor don't seem to contribute too much to engineering demands on accuracy and documented proofs.
RE: Pressure Drop Formula
I'm not too surprized you found problems. I didn't expect to see it included surge, but since it is so very easy to include elevation differences in such a program, and such an annoyance when they arn't, it indicated to me that it was a pretty lazy programmer that wrote that one up. From what you say, it may have been much more than laziness. Now that you mention it I also believe it has not been fixed yet.
And yes, back in the "old days"... we would spend a great deal of time throughly testing all software products we purchased to validate the results before they were allowed to be used on the floor. I still see "real" professional engineering companies doing this, where the use of such programs for project work is banned. Applets are allowed to be used ONLY to get preliminary non-design use numbers (WAG), but no such results can form any part of officially documented work to be handed over to a client. Only approved programs can be used, and, in fact, all engineers are not permitted to write any personally written spreadsheets, without preapproval to do so. Most clients I've worked with have also had lists of programs that were approved for use on their projects as well, and if you didn't have those programs in-house, you didn't need to waste your time bidding for their work.
Well, all in all I guess I shouldn't compain. It might just mean more business for me next year fixing those engineering BOT designs. How do I love this internet? Let me count the ways.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
Art, it seems that EngineeringPage have taken your comments to heart and fixed whatever was wrong. I just plugged in your data and got a pressure drop of 1.09 psi. It is very disconcerting when a program gets a simple calc like this wrong.
I am very surprised that they have not written back to you thanking you for your help. As a software author myself, I know how difficult it is to test for every eventuality and I am always very grateful when users write back to me to point out problems.
BigInch, as I am sure you have experienced, in addition to using only approved software large contractors check all critical calcs by independent means. Even the best software carries a disclaimer and it is up to the engineer to interpret its output. I find that these little applets are useful for the independent checks because I cannot afford to purchase all the serious software. Unfortunately Art's experience is not unusual and many of them have wrinkles in them. And as a final check many engineers will pull out their copy of Crane and use the relevant chart to ensure they are in the right ballpark.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure Drop Formula
I thought I just got what was a high dP for 100 m3h in 100 m of 6". ... maybe not. Anyway, still no elevation diff.
I usually have my own programs of one kind or another to use for checking, so I don't often have to revert to applets.
In addition to that, I never did my first design on any particular item, without having someone with tons of experience reviewing my work. Afterwards, still had a super looking over my shoulder and answering any questions I had. From the looks of many questions that get posted on all of these forums, there's a lot of people today that either do not have qualified managers they can turn to, or they do not feel comfortable asking them questions; either one of which is a travesty to the field.
Oh by the way, thanks for your unit converter. I haven't found a useful unit you've left out of it yet and it does have pleanty of the good ones. Best engineering unit converter I've seen anywhere. Really a good creation there.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
Like you, I was very fortunate to start my career under some very competent engineers who had a great way of pointing out errors without laying blame. I still feel an obligation to pay this back to the engineering fraternity and I help youngsters where I can. Unfortunately South Africa is just like the rest of the world where there are fewer and fewer mentorship opportunities.
This is one of the factors that makes Eng-Tips such a useful resource and is why I try to help where I believe the posters are making a genuine effort to better themselves. That sounds rather arrogant - I still learn more here than I teach, but it is one of the very few avenues where we can put back something in return for the benefits we enjoyed.
Harvey
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure Drop Formula
Consequently I never have to take a black-box program on faith. I can just open my notebook and quickly verify the answers with equations that I trust. If the black box is significantly different from my notebook then I don't bother with it any more (I just don't write those, "I think you may have screwed up" e-mails).
David
RE: Pressure Drop Formula
How about the below post which has recieved only one response?
sailoday28 (Mechanical)2 replies20 Oct 06 (18 Oct 06)
isothermal choked flow of perfect gas
Regards
RE: Pressure Drop Formula
RE: Pressure Drop Formula
NO, no no! I was referring to the webmaster, the addressee of Monte's letter, that never bothered to respond with a simple thanks. I can only say
Right, I believe the only bad questions are the ones that go un-asked. I also try to help by returning what I can back into the profession, although it is pretty hard to match the typical quality of responses found on these forums, I try anyway. In the meantime I soak up all the great conglomeration of experience that manages to make its way here.
wfn, Thanks for being conscientious and responsible!
I still say they need to add the elevation difference to make it really useful, but maybe we should let zdas write that letter.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
RE: Pressure Drop Formula
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
RE: Pressure Drop Formula
I guess if the line was eventually looped, you didn't win that battle for quite awhile after initial construction?
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure Drop Formula
RE: Pressure Drop Formula
RE: Pressure Drop Formula
More interesting now then is how the pipeline managed to get built with the smaller diameter. What happened there? How long did they try to run it before looping it?
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
Pd = 4.73 x L x (Q/C)1.85 / d4.87
where
Pd is the Pressure drop
L is the pipe length in feet
Q is the flowrate in gpm
C is the Hazen Williams friction factor
d is the pipe ID in inches
Where did you use the density? Was it only to convert the mass flowrate to the volumetric flowrate Q? How different is the density of super-critical ethylene from water? By how much did the density vary over the length of the pipeline? How did you convert the Moody friction factor into the H-W C form?
Sorry for all the questions, but I cannot see how you got a good answer with this procedure.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure Drop Formula
RE: Pressure Drop Formula
What's in a name? that which we call a rose
By any other name would smell as sweet;
You can call Darcy Weisbach whatever name your like, and it stays just as accurate.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure Drop Formula
....And the sleuth got it right when he said, "Elementary, my dear Watson."
Leave it to Harvey to get to the bottom of the mystery and discover what did the Pipeline in: it was Henry Darcy (& Julies Weisbach helped him do it)!
Harvey, you deserve a lot more stars than my single one for the excellent detective work. I hope that tight wad, Big Inch, gives you one as well.
RE: Pressure Drop Formula
And if my equation isn't the precursor to the HW equation, I apologize for being misleading. Put I love the excel sheet. Like I said, I even replace the density lookup with a density calculation using a simple direct solution for zfactor to get gas density.
RE: Pressure Drop Formula
Your analysis makes a very important point, which has got a bit lost in the queries over the name. You have shown that doing a rigorous analysis, breaking the pipeline up into small sections where each one can be regarded as incompressible flow is much better than an empirical estimation like Panhandle B. Those formulas had their place when engineers didn't have spreadsheets at their fingertips, but we shouldn't use them any more. I have used your technique of simply copying a spreadsheet line down 100 or 1000 times and breaking a problem down into subsections where the properties can be regarded as constant for a multitude of problems - not just fluid flow.
The Hazen Williams formula (the real one!) is of a similar nature to Panhandle B in that it is an empirical estimation. It was derived for water, whereas Panhandle belongs to the petroleum industry. We sometimes lose sight of just how much genius there is in the Darcy Weisbach analysis because it looks so simple and we use it every day, but it replaces and improves on a myriad of old formulas. It is one of the great triumphs of engineering.
Meksen, if you are still following this thread after we highjacked it, in the end the thread has answered your original query quite well - stick to the real thing and use Darcy Weisbach and don't be drawn into using any of the old estimation formulas. Buy a copy of Crane (did I say that before???). Good luck.
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Pressure Drop Formula
I knew from the very second dc said "HW", that he was messing around with us. Look at "how" I asked the question. The rest just confirmed my suspicions. I simply resisted the urge to push that directly and went for the more interesting story.
Monte,
TIGHTWAD! ??? I just checked this. Monte, the rate at which you hand them out is 14% of my rate. You see, you've given 96 votes and have been a member since 2001 (2005 days) for a rate of 0.0179 votes/day, me only a member for just 130 days, but I've given 45 votes already! Rate: 0.346 votes/day. Hey just kidding. Noticed you're in Spring. I learned to fly out at the old Collier and DWH airfields, pumped jet into Arnold Palmer's Lear at DWH in 1968, and I even told him... thank you.
As for all the rest of you, change to Churchill and you'll all be in much better humor when you don't have to make any friction factor iterations.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
Just wanted to pull your chain & see if you were awake. You killed me with your logic and facts - just like Darcy-Weisbach.
Try Serghides for explicit calculation of the Darcy Friction Factor. I think you'll like the accuracy and the simplicity. I think Harvey is a Churchill man also.
Have a good day. I think we've sold enough copies of Crane's Tech Paper #410 for the duration of the week.
RE: Pressure Drop Formula
Is there a commission on those sales?
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula
I would never trust detection and engineering go hand in hand, for engineering is more human
However, I couldn't resist myself giving BigInch a star.
RE: Pressure Drop Formula
I recently passed my Diploma and was given this forum by one of our client and everytime I visited it, it encouraged me to go back to school and study further
Thanks all for all your discussions
RE: Pressure Drop Formula
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Pressure Drop Formula