Friction Loses in pipe ASTM A106 1

[Saver2008]

Hi everybody!

I`m trying to calculate the total pressure drop in a steam pipe system. I`m pretending to use the bernoulli equation but when I see the part of friction loses equation, I saw that I require the Darcy Weisbach equations but as I have understood, this DW equation works with WATER and with some common and general materials. I`m trying to find out the pipe friction coefficient for ASTM A106 Gr B or other from ASME Secc II. (just pipe). And also I`m trying to find the resistance coefficient for fittings (in my case just elbows of 90 and 45 grades)....anyone can tell me where can I find this info?

Thanks!!!
RS

 

[SNORGY]

If your total pressure drop is less than 10% of inlet pressure and you are not anticipating substantial condensing, then Darcy Weisbach will work.

You should invest in a copy of Crane Technical Paper 410. It is less expensive than most modest textbooks, but ten times the value.

 

[Saver2008]

@SNORGY Thank you very much Snorgy. I calculate the pressure loss just considering different heights and length and I`m having more than 10% of inlet pressure...and I`m not considering the fittings and the roughness of inside pipe. As I have insulation on pipe, I will not have condensing on the system...Darcy weisbach can still work? What do you think?
RS

 

[SNORGY]

Try breaking the pipe up into smaller segments and use the outlet conditions from the previous segment as the inlet conditions for the next segment, and so on.

You could Google the Spirax-Sarco website and check out their methodologies, charts and on-line calculators. They are pretty reliable.

 

[TD2K]

What are the steam conditions, line size and length? We can do a quick check for a section and see if your approach is correct.

For steel pipe, I usually use the pretty typical 0.00015 feet for roughness. Fitting losses (elbows, tees, full open valves, reducers, etc) are typically handled in terms of L/D. There are lots of formulas for calculating the friction factor or you use the standard Moody diagram in Crane (if you don't have a copy and are doing to do hydraulics, get one yesterday).

There is also Fanning friction factor and a Moody friction factor. Be sure to know which friction factor your pressure drop correlation is based on if you start using different correlations from different references.

http://www.eng-tips.com/faqs.cfm?fid=1746

 

[BigInch]

Read everything here, then start over.

http://www.spiraxsarco.com/resources/steam-engineering-tutorials.asp

Especially this page,

http://www.spiraxsarco.com/resource.../steam-distribution/pipes-and-pipe-sizing.asp

What would you be doing, if you knew that you could not fail?

 

[Saver2008]

Thank you all of you. In spirax sarco web site comes what I need.

Thanks again!!!