Roughness of cement lined ductile iron pipe
Roughness of cement lined ductile iron pipe
(OP)
Does anyone have a reference for the roughness of cement lined ductile iron pipe? My hydraulics book shows roughness for various types of pipe including ductile iron but it does not specifically say cement lined. An engineer at a water district said he thought it was about the same as PVC but that just sounds way too smooth.
Thanks,
DPAJR
Thanks,
DPAJR





RE: Roughness of cement lined ductile iron pipe
RE: Roughness of cement lined ductile iron pipe
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RE: Roughness of cement lined ductile iron pipe
It sounds reasonable to me. Other "cement" related info I have is "smoothed concrete" at 0.5 mm and "asbestos cement" at 0.05 mm.
For rigid PVC piping I would use a value of 0.005 mm, so I would agree with you that your colleague is being a bit optimistic.
regards
Harvey
Katmar Software
Engineering & Risk Analysis Software
http://katmarsoftware.com
RE: Roughness of cement lined ductile iron pipe
RE: Roughness of cement lined ductile iron pipe
Does anyone know of problems with the cement lining in situations where you have 15 fps? The situation has no possible surge (partial pipe flow with no valves) and there are no pumping costs.
RE: Roughness of cement lined ductile iron pipe
Use of Hazen Williams is considered to be less accurate than Darcy Weisbach especially in larger sizes.
Was this is in the water distribution forum I take it that the fluid is water and not sewage or a slurry. The velocity of 15fps is only a problem if you have a long line . The head loss will result in high energy costs. Gravity lines often flow at velocities much higher than this figure.
Geoffrey D Stone FIMechE C.Eng;FIEust CP Eng
www.waterhammer.bigblog.com.au
RE: Roughness of cement lined ductile iron pipe
RE: Roughness of cement lined ductile iron pipe
The tolerance on cement linings is as great as the wall thickness tolerance in plastic pipe wall thicknesses. The difference is the cost of the material. The plastic material costs far more than the cement lining. Hence plastic manufacturers use every device available to manufacture to the tightest tolerance, ie thinnest wall. They make money by selling you the least amount of product that meets specification.
Whereas the cement is a very minor part of the cost of DICL pipe. It doesnt require energy to melt it as does the DI. So manufacturers of DICL put all their effort into the DI side of things.
Geoffrey D Stone FIMechE C.Eng;FIEust CP Eng
www.waterhammer.bigblog.com.au
RE: Roughness of cement lined ductile iron pipe
My ref book "The Hydraulics Handbook" published by the Nat'l Fire Sprinkler Assn use a C factor of 140 (Hazen-Williams formula).
Also, reference NFPA 13 Instlln of Spklr Systems, by Natl Fire Protn Assn, which in table 14.4.4.5 states the Hazen-Williams C-factor as 140.