Absolute pipe roughness and surface finish of pipe
Absolute pipe roughness and surface finish of pipe
(OP)
For pressure drop calculations, Crane's Handbook and many software give the absolute roughness of Pipes as 0.05 mm for clean commercial steel pipes
What is the surface finish (RMS or Ra) to be specified to the pipe manufacturer to attain the above absolute roughness.
Is there any correlation between RMS value and absolute roughness of pipes used in friction drop calculations
What is the surface finish (RMS or Ra) to be specified to the pipe manufacturer to attain the above absolute roughness.
Is there any correlation between RMS value and absolute roughness of pipes used in friction drop calculations





RE: Absolute pipe roughness and surface finish of pipe
RE: Absolute pipe roughness and surface finish of pipe
RE: Absolute pipe roughness and surface finish of pipe
you could try "polished", but if you want something better than the standard 20 - 45 micron (.001mm) level which has been recognized as the default standard range for new steel pipes, then you need to coat it or line it with something.
epoxy coatings are normally good for about 5 - 8 micron and PE is usually thought of as 3-5 micron.
I'm struggling to think that a steam line is long enough for the absolute roughness to be a significant issue.
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RE: Absolute pipe roughness and surface finish of pipe
My doubt is whether the surface finish given by Pipe vendors can be treated equivalent to a hydraulic roughness of 0.05 mm as specified in CRANE Handbook, or should I take a higher roughness value for Pressure loss calculations. Or should I insist on the Pipe vendor for an acceptable surface finish which can be treated equivalent to a hydraulic roughness of 0.05 mm
LITTLEInch has thrown open another question to me for which I dont have an answer whether surface roughness plays a role in a Superheated Steam line of 170 ata, 540 deg C
RE: Absolute pipe roughness and surface finish of pipe
The second main reason for being interested in the roughness is for hygiene and cleanliness considerations. This can be important in the pharmaceutical and food industries, but usually does not bother us with steam flow.
While it is true that roughness is more important in gas flow than in liquid flow (because of the high Reynolds numbers preventing hydraulically smooth flow) I have never found a situation where it impacted on a steam line. If you are pumping natural gas thousands of kilometers then a smoother pipe can save you significant amounts of energy, but if your steam line runs at a slightly lower pressure drop it probably only means that your control valve will settle out a bit less open.
Katmar Software - AioFlo Pipe Hydraulics
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Absolute pipe roughness and surface finish of pipe
RE: Absolute pipe roughness and surface finish of pipe
David Simpson, PE
MuleShoe Engineering
In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist
RE: Absolute pipe roughness and surface finish of pipe
RE: Absolute pipe roughness and surface finish of pipe
Katmar Software - AioFlo Pipe Hydraulics
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Absolute pipe roughness and surface finish of pipe
RE: Absolute pipe roughness and surface finish of pipe
Katmar Software - AioFlo Pipe Hydraulics
http://katmarsoftware.com
"An undefined problem has an infinite number of solutions"
RE: Absolute pipe roughness and surface finish of pipe
Perhaps you can explain why an increase in surface roughness should lead to an increase in required pipe size.
RE: Absolute pipe roughness and surface finish of pipe
RE: Absolute pipe roughness and surface finish of pipe
RE: Absolute pipe roughness and surface finish of pipe
In some cases, where there is a control valve downstream or some device which is somewhat tolerant of variations in its inlet pressure, perhaps you may not have to change line size with the higher roughness. In other cases, maybe you should move to a bigger line.