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HW C factor for relined water main.
2

HW C factor for relined water main.

HW C factor for relined water main.

(OP)
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.

RE: HW C factor for relined water main.

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.

RE: HW C factor for relined water main.

(OP)
We are doing cement lining.

RE: HW C factor for relined water main.

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" ?

 

RE: HW C factor for relined water main.

(OP)
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.

RE: HW C factor for relined water main.

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   

RE: HW C factor for relined water main.

CORRECTION:

That should be "DW-epsilon        1 -  10"

RE: HW C factor for relined water main.

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 http://www.haestad.com/books/pdf/awdm.pdf 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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