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HW C factor for relined water main. 2

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davidgb

Civil/Environmental
Feb 25, 2005
3
We are cleaning and lining old 6" dia. cast iron water mains. What Hazen-Williams C factor should I expect once completed? They are currently 16 and 31.
 
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It depends on what you are lining it with. The vendor of the lining product should be able to give you a good range of HW Cfactors.
 
We are doing cement lining.
 
Do you mean the HW-C factor of the unlined pipe is currently 16, or 31 ? This is very low. How do you know this ? Was it measured during a flow test ? If it was measured, can you measure the C of the relined pipe ?

Better yet, can you measure the Darcy-Weisbach friction factor "f" ?

 
It was measured using a parallel hose C-factor test and we intend to do the same after it is lined. I am looking for what numbers to expect after lining. Yes the numbers are now very low (there are two different streets) hence the need to clean and line the mains.
 
Published factors for 6-inch, cement mortar lined DIP are:

HW-C 120 - 140
DW-epsilon 1 - 110
Manning's n 0.012 - 0.017

good luck
 
CORRECTION:

That should be "DW-epsilon 1 - 10"
 
I would think that there might be some difference in flow coefficient realized for factory cementlined pipes vs old unlined pipelines that are in-situ cementlined long after their original installation (and long carrying aggressive water).

Notice e.g. that per the table “C-factors for various pipe materials” in Appendix C of the “Advanced…” reference at that slightly lower C-values are given by this source for “Tate relined pipes – clean” (I believe “Tate” in fact refers to a well-known international in-situ cement mortar liner).

In any case, it appears you may have an opportunity to notably improve the flow performance.
 
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