corrosive water pipe 1

[johnhjo]

Hi,

I have installed galvanize (medium type) pipe in office building. Within 3 months most part of pipe leaking. I cut them apart, found lots of sediment and corrosive cavity inside pipe. Finally, I get water sample and analyze it with result:
- Mg : 14.1 miligram / liter
- Ca : 47.3 miligram / liter
- Cl : 59.4 miligram / liter
- SO4 : 93.9 miligram / liter
- pH : 7.5

Right now We are not sure wheter the problem is on pipe's quality or the polute water causing such damage.

Any idea/ advise about this?

Thanks

 

[kenvlach]

Try to get a copy of Internal Corrosion of Water Distribution Systems, 2nd Edn., ISBN 0-89867-759-9 (1996). Chapter 3, Corrosion of Galvanized Pipe (pages 71-129), is pretty thorough.

Your descriptions suggests 'all-over' corrosion indicating that galvanized pipe is not compatible with the water. Any weaknesses (poor weld quality) would show accelerated attack, as would pipe next to dissimilar metals such as brass valves.

Can you do any treatment of the water (raise pH to 8.5, add 2 ppm orthophosphate)? Also, verify that dielectric unions weren't omitted.

 

[bimr]

As kenvlach suggests, raising the water pH to 8-8.5 units should solve the problem. You should use a chemical such as sodium carbonate to raise the pH since sodium carbonate is less hazardous than other chemicals.

If you want to look further into the water, you need a complete water analysis.

The water quality parameters that you should obtain for a project are the basic drinking water quality parameters.

Most labs sell a Basic Water Quality Chemistry Package that contains:

pH
Conductivity and
Corrosion Index
Total Dissolved Solids
Total Suspended Solids
Total Coliform
Alkalinity
Iron, Manganese,
Copper,
Sodium
Calcium,
Magnesium ,
Potassium,
Zinc
Nitrate and Nitrite
Chloride,
Sulfate,
Chlorine
Total Hardness

The labs do this complete package for less than $100.

Maybe this old thread will help:

http://www.eng-tips.com/viewthread.cfm?qid=80889

 

[johnhjo]

Thank you for respond.

Actually I would like to know which chemical really damage galvanized pipe. and find a device to help reduce its volume so I dont have to pour any chemical.

 

[bimr]

The chemical that is probably damaging your pipes is carbon dioxide. Sodium carbonate will neutralize carbon dioxide.

Suggest you contact a water conditioning expert such as someone from firms such as Betz, Chemtreat, or Nalco for further assistance.

 

[dicksewerrat]

Also check on the grounding of the system. you may have some low voltage leaking through the pipe.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[equimo]

This is a kind of situation in which I ask why having this corrosion problem dealing with forever trying to get a better quality of water? Why don't use other type of pipe material like SS, copper, or PVC (protected by steel pipe in case that expose to hard conditions that seems to be the concern)