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Hazen-Williams Coefficients Table
The Hazen&#;Williams equation has the advantage that the coefficient C is not a function of the Reynolds number , but it has the disadvantage that it is only valid for water . Also, it does not account for the temperature or viscosity of the water.
The following are Typical C factors used in the Hazen&#;Williams equation, which take into account some increase in roughness as pipe ages are as follows:
Material Hazen-Williams (C) ABS - Acrylonite Butadiene Styrene 130 Aluminum 130 - 150 Asbestos Cement 140 Asphalt Lining 130 - 140 Brass 130 - 140 Brick sewer 100 Cast-Iron - new unlined 130 Cast-Iron 10 years old 107 - 113 Cast-Iron 20 years old 89 - 100 Cast-Iron 30 years old 75 - 90 Cast-Iron 40 years old 64-83 Cast-Iron, asphalt coated 100 Cast-Iron, cement lined 140 Cast-Iron, bituminous lined 140 Cast-Iron, sea-coated 120 Cast-Iron, wrought plain 100 Cement lining 140 Concrete 120 Concrete lined, steel forms 140 Concrete lined, wooden forms 120 Concrete, old 100 - 110 Copper 130 - 140 Corrugated Metal Pipe 60 Ductile Iron Pipe (DIP) 140 Ductile Iron, cement lined 120 Fiber 140 Fiber Glass Pipe - FRP 150 Fire Hose (Rubber Lined) 135 Galvanized iron 120 Glass 130 Lead 130 - 140 Metal Pipes - Very to extremely smooth 130 - 140 Plastic 130 - 150 Polyethylene 140 Polyvinyl chloride, PVC, CPVC 140 Rusted Steel 140 Steel Coal-Tar Enamel Lined 145 - 150 Steel Forms 140 Steel new unlined 140 - 150 Steel, corrugated 60 Steel, welded and seamless 100 Steel, interior riveted 90-110 Steel, interior riveted, no projecting rivets 110 Steel, projecting girth and horizontal rivets 100 Steel, vitrified, spiral-riveted 90 - 110 Steel, welded and seamless 100 Tin 130 Vitrified Clay 110 Wrought iron, plain 100 Wood (well planed) 130 Wooden or Masonry Pipe - Smooth 120Related Resources:
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Roughness of cement lined ductile iron pipe
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(Civil/Environmental)
(OP)
29 Jul 06 12:02Does 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
(Civil/Environmental)
29 Jul 06 16:29Try Googling DIPRA
(Petroleum)
30 Jul 06 03:03I've not used cement lined pipe, so I don't know. If you have some around, you could you measure it.
Going the Big Inch!
http://virtualpipeline.spaces.msn.com
(Chemical)
30 Jul 06 10:06The value I use is 0.1 mm for a spun cement lining. Unfortunately I did not make a note of where I got that info - it is just a note in my file that I made at some stage.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.regardsHarvey
Katmar Software
Engineering & Risk Analysis Software
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(Civil/Environmental)
30 Jul 06 15:04I typically use a value of C=120 for design of DIP for water supply. New pipe may be closer to 130 but 120 is a conservative number.
(Civil/Environmental)
31 Jul 06 09:32My American Ductile Iron Pipe manual suggests a Hazen Williams c of 140 to 150 or higher for high speed cement lining or large pipe sizes. I would use 120 for older existing pipes as cvg suggests for long term or sensitivity analysis. Same as PVC depending on your connections.
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.
(Mechanical)
31 Jul 06 19:46Roughness when new is .010mm. However deepending on service this can increase to as much as 3mm. Also slimes build up will decrease the diameter and this will have a more drammatic effect on the fluid flow. Unless the fluid is particulalry agressive then a roughness of 0.30mm could be used for a fifty year life.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
(Civil/Environmental)
9 Aug 06 11:42It is probable your colleague is essentially right -- I think most contemporary ductile pipe cement mortar linings are from a hydraulic perspective rather smooth, as the centrifugation of the applied lining can make the flow path reasonably consistent in all directions and the lining in addition maintains flow properties in even some quite aggressive water services for a very long time (by not fostering significant growth of tuberculation as was encountered in unlined pipes in aggressive exposure). Also, it should perhaps be emphasized that actual hydraulic performance of pipelines is probably dependent on more than hype/perception or manufacturer&#;s claims, or even smoothness to the touch of a localized area of e.g. plastic piping material. e.g. the actual flow areas of the same nominal size of different material types of AWWA pipes is commonly not the same. The internal diameter of most common (minimum in small sized pipes) Pressure Class 350 ductile iron pipe is larger than the internal diameter of most commonly specified pvc and hdpe pipes, per the respective, comparative AWWA standards. Actual pipe flow area has of course much influence on hydraulic performance per virtually all formulae approaches. While most solid wall plastic pipes are rather smooth on the outside, some experts have apparently also noticed that at least some plastic pipes have &#;waves&#; or undulations on the inside and of course are more subject to long-term ring deflections that apparently can arguably at least to some extent affect hydraulic performance (see e.g.comparative data in the &#;C.Tables&#; from e.g. Haestad/Bentley&#;s &#;Advanced Water Distribution Modeling and Management&#;, at http://www.haestad.com/library/books/awdm/online/wwhelp/wwhimpl/java/html/wwhelp.htm ). I believe additionally some P.E.'s with DIPRA (dipra.org) have worked with some interested actual utilities to run sort of comparative side-by-side flow testing/comparisons of actual working ductile iron vs plastic pipelines in their systems, and they may have some reports available of these tests.
(Mechanical)
9 Aug 06 21:20rconner is correct. Diameter is more significant than roughness in hydraulic calculations. Although he is part of the ductile pipe industry, he does provide technical correct information.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
(Civil/Environmental)
15 Aug 06 10:02We commonly use cement lined ductile iron underground private fire service mains in the fire spinkler industry.
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.
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