HW C factor for relined water main. 2

[davidgb]

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.

 

[coloeng]

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.

 

[davidgb]

We are doing cement lining.

 

[RWF7437]

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" ?

 

[davidgb]

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.

 

[RWF7437]

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

 

[RWF7437]

CORRECTION:

That should be "DW-epsilon 1 - 10"

 

[rconner]

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.