"Galvanized Pipe Corrosion"

Question:

"I have a question in regard to the effects of high sodium level (971 mg/l) well water will have on galvanized pipe. The temperature of the water is 65 F. The corrosivity is listed as "non-corrosive" in an analysis report using the Langlier's as the method. Will the high sodium increase the corrosion or effect the galvanizing in any way?"

Answer:

Sodium is a component of the total dissolved solids content of water, with respect to the Langlier index. As a consequence, it contributes to the scaling tendency of water, as measured by the index. Water with scaling tendencies tend to be non corrosive, as they precipitate a protective calcium carbonate scale on the metal surface. Therefore, sodium's effect on corrosion of galvanized pipe should be primarily based on how it influences the scaling tendency of the water, assuming that the ionized form of the sodium species does not depress the pH of the water. The zinc (galvanized) layer will slowly dissolve based on several water quality factors, including conductivity, velocity, microbiological activity, Langlier index value, temperature, etc. There is much data on the corrosion of black carbon steel and galvanized carbon steel pipe in potable water.

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