Here is a link to the Moody chart.

And yeah it is generally accurate in the 10^5-10^6 range.

The other link is people discussing the surface roughness (e) values for 5L pipe (180micro-inches or 0.04572mm.) I do not mean to be rude, but less than 5 minutes of googling would have given you the answers.

http://www.pipeflow.com/pipe-pressure-drop-calculations/pipe-friction-factors

http://www.eng-tips.com/viewthread.cfm?qid=322259

Thank you.

Another straight forward approach is to use swamee - jain equation, which is fairly accurate.

Is it an implicit or explicit eqn. dear Arun?

It does not require any iterations like the colebrook equation. Its a straight forward equation to determine the darcy friction coefficient provided you have the data - pipe roughness, internal dia and reynold's number for your problem.

you can find the equation at the link (google-ing):

http://www.kolumbus.fi/jukka.kiijarvi/clunowa/fluid_mechanics/pdf_articles/darcy_friction_factor.pdf

refer equation no. 5 section 2.4

Also I have produced a lecture notes for IMU students regarding this pipe line fluid flow. You can download my notes at:

http://upload.wikimedia.org/wikipedia/commons/b/b5/P%26ID_Lab_Theory.pdf

You will find the guidance useful

Actually I was using a different application. I know the Re & have calculated friction factor from the formula(I know the pressure drop, pipe dia. & length) but I don't know the roughness, bcoz my pipe is 50 years old (petroleum pipeline) that has been pigged 4 times a year.

Hmm... since you have plotted the system curve of the test section and aware of the minor losses, you can isolate the major losses and its possible to evaluate the roughness. Just do a reverse calculation from the formula of swamee-jain. you can calculate the e/E ratio. Now if you can estimate the average diameter of the pipe you are there. e can be calculated, which will be your pipe's roughness.

BTW, I hope its a crude oil pipe and its being pigged. Pigging will have a tendency to dislodge the loose rust and you may have a smoother pipe internals !

Pay attention to the use of Swamee and Jain formula. It can cause 3% error in the calculation of the friction factor. View the article at http://www.academicpub.org/jces/paperInfo.aspx?PaperID=565

Dear Arun, since its a Product pipeline, not a crude one, there is negligible change in dia. I am unable to guess that whether the scratching of the pipe by PIG brush increases roughness or decreases it by removing deposits. actually I am getting Darcy friction factor=0.014 at Re=125000 that suggests an almost COMPLETELY SMOOTH surface like glass. Is it possible? please refer my publication

Sadaf, I had a quick glance at your paper --- I have enumerated my observations, which I hope will answer your doubts and clarify on few aspects.

1. The journal you are working with requires scrutiny. I have earlier read that this is not a genuine journal. Getting good peer review is not possible with these publishers.

2. Pigs serve various functions - two of which should interest you are (for the nature of piping you have mentioned) - cleaning pigs and sealing pigs.

3. There should be pumping and pigging log reports maintained by the stations. Which will summarize operational parameters which will be of great help to the assessment team.

4. When some increase of pumping power is observed you should do a cleaning pig operation. Your IOCL formula is an interpretation of this concept. It says flow achieved per unit pressure drop. It is an indication of pipe line deterioration, as decreasing flow rate achieved per unit pressure drop, shows increased resistance or increased pipe line friction.

5. When pumping two different grades of products use only a SEALING PIG ! so you should find two different types of pigs being used. But your paper mentioned only about cleaning pig (one with brushes).

6. The cleaning pig effectiveness should be quantified on the basis of nature of deposits that you observe at the pig trap points. If you get more deposits afer one pigging operation, repeat it. If not commence your operations with sealing pig.

7. When using sealing pig during pumping of different grades, make note of average pig speed and flow velocity. If you are getting a large difference between the flow velocity and the average pig speed, it shows that there is some slippage past the pig and the operation is ineffective.

8. The fluid pipe line flow equations are an approximation when working with completely filled pipelines. If not there is a scope for huge error. You should first focus on the geometry of the pipe line section and its fill ratio before applying the fluid flow concepts. Other wise results do not convey any meaning.

9. Pipe line roughness and internal conditions can also be verified using monitoring pigs. Pipe line should be fitted with pig loggers to track movement of the pig.

I stop at this point for brevity. I hope you will find the points notable.

Thank u Arun Sir. I agree with most of your observations. Some point wise explanations are as below:

4. Actually IOCL formula would better apply for pipelines having large product batch-lengths(as in Gujarat) that completely fills the pipeline between two consecutive pumping stations, that is never the case in UP. Going by the IOCL formula, we were often getting negative 'efficiency'. My paper actually focuses on this aspect. I have tried to show therein that how even if the surface roughness is reduced by Pigging, we can have an increased friction factor in our case where we are having small batches of diesel, petrol etc filled in b/w consecutive stations due to considerable change in viscosities.

5. I would check for this. Actually for long time we have been using Bi-Di Pigs. And foam pigs are used once in 2-3 years.

6. We are having carbonates, sulphates & oxides of Fe along with evidence of Sulphur reducing bacterias. Actually it is practically impossible to quantify the contents of deposits bcoz it depends on time, no. of batches passed, viscosity of various batches, shutdown period & many more. But, I believe in your idea of frequently using sealant Pigs.

7. Yes we calculate Slippage of PIG. But again, due to changing flow rates & delivery pattern it is not realistic in our case of 12" pipeline.

8. This is very much agreed. Please share if you have any paper on this aspect & oblige.

9. please tell what kind of instrument is required for online roughness measurement. Actually we have I-Pigs for recording & monitoring of pipe thickness but not for roughness.

Thank you very much for value addition

Dear sadaf,

8. The pipe line fluid flow means that flow cross section is same as internal area of the pipeline. If the pipeline is part filled, how can you use pipeline flow calculations ? It becomes a channel flow ! Your fundamental flow equation Q = A.V to reynolds number to all other calculations use diameter of the pipe right ? So this is obvious.

9. Just google 'intelligent pig' you will have the world of information before you. Also visit http://www.nov.com . They are one of the pioneering firms and designers of tuboscopes.

No no Arun. pipe is never partly filled, there is no question of channel flow. I was talking of the vapour of products that might be occupying say .1% of the pipe area.

How can you state that the pipeline is full ? How is the pipeline designed for that ? What is variation of the pipeline above ground level ?

What is line fill volume between the sections you are measuring.. ? How are the batches of products pumped into the same line ?

The line has been designed keeping in mind the topography of land during pre-construction survey. It is ensured that some residual pressure must always be there at the highest point. As the line is always pressurized this implies that it is always completely filled. If you assume that pressure falls to zero at any point, then flow will cease. The line fill volume is known to us. The different batches are being pumped by changing over the tanks having different batches.

Pressure in a line does not mean that it is completely fill.

I feel you should first prove that the line is completely fill and then apply pipeline flow.

Pipe line can be filled by careful analysis and only with use of pigs mostly. With analysis, I mean sufficient experience in estimating flow required and choice of pigs. Even with this approach it is said that during hydrotest of the lines it is acceptable if gas volume in the pipeline is about 0.2\%, as 100\% filling is difficult to achieve in a well laid line. Now if your line at any point is sloping down and or since you are not using pigs during usual operation, the pipeline may not be full.

You should not attempt to decipher pipeline smoothness by reverse engineering the pipeline liquid flow concepts in your case. It is for this reason the pipeline transportation firms have developed a lot of monitoring equipment to gauge the pipeline internals.

If you are still confident of your approach, you should prove that the lines are full.

Exactly. as I said earlier I am not sure about vapour content. But Still it should not be an open channel flow, bcoz the vapours here are at high GAUGE pressure. So it would be complicated, not like open channel flow.

I never mentioned open channel. I said channel like flow. I hope you can now go on with your work. I tried my best to guide you.

thank you Sir