Acceptable corrosion for copepr potable water pipe 2

[MedicineEng]

Hi All:

In our property most of our cold and hot potable water distribution is in copper pipe. Given the size of the property we have an in-house chlorine dioxide production and distribution plant in order to avoid microbiological growth.
Of course one of the drawbacks of this technology is the added corrosion rate in pipes, so we have to strike a balance between keeping the bugs in check and not having pipe leaks due to corrosion.
I was looking for some standard on the recommended/acceptable corrosion rate for copper pipes (mils/year or mm/year) in potable water installations but I couldn't find anything. I heard that anything <1mil/year is good but couldn't find anything from any reliable source and I'm not sure where this came from.

Anyone has any idea on this?

Thanks.

 

[EdStainless]

You could take the design life and work backwards.
Assume a 80 year service ...
The real issue isn't general corrosion, it is localized attack.
Especially in high velocity areas such as elbows and tees.
And of course there is the issue of Cu in the water, I hope that you test that.
The action level is 1.3ppb as I recall.

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P.E. Metallurgy, Plymouth Tube

 

[moltenmetal]

Why are you using chlorine dioxide? Chloramine is the more usual choice for residual disinfection in potable water, isn't it?

 

[bimr]

The corrosion rate of copper will be dependent to a large degree on the water quality which you have not mentioned.

Copper tubing is thin wall material and is susceptible to erosion from flow velocities above 8 ft/sec. Copper is also susceptible to MIC and corrosion from low quality potable water.

Copper.org is the best source of information.

Copper Corrosion

 

Erosion corrosion in copper hot water lines carrying city water also kicks in with a vengeance above about 60°C (140°F).

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[MedicineEng]

Hi All:

Moltenmetal:
Chlorine., Chlorine Dioxide and Chloramine are all accepted and widely used residual disinfection methods. Each has it's own advantages and disadvantages.

Bimr:
The potable water quality meets all chemical and bacteriological requirements of EU and WHO standards for potable water. The main potable water source is from river, so it is relatively soft when compared with ground water.
Thanks for the hint on copper.org. I'll try to spend sometime there and see if I can find something related with this issue.

 

[GGedge]

You might find this guide of some help.

The section on cuprosolvency might be relevant to a large property if parts of it do not see regular throughput of water.

Cheers

GG

 

[bimr]

The potable water quality meets all chemical and bacteriological requirements of EU and WHO standards for potable water. The main potable water source is from river, so it is relatively soft when compared with ground water.

Note that a water may be corrosive despite meeting all chemical and bacteriological requirements of EU and WHO standards for potable water. In addition, whether the water source is from a river or ground water well has no impact on the water hardness.

 

[btrueblood]

What is the pH of the water?

 

[MedicineEng]

bimr:
River water is typically less hard than water from underground aquifers.

btrueblood:
Currently our incoming water is pH=7.9 and 90 ppm total hardness.
Thanks

 

[EdStainless]

With river waters you need to pay attention to seasonal changes.
There are places where the Mn and Fe levels really spike in the autumn.
And if you are anywhere near the ocean you need to watch Cl incursion also.

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P.E. Metallurgy, Plymouth Tube