SCC of 304/316SS
SCC of 304/316SS
(OP)
Can normal levels of chlorine in potable City Water cause SCC in 304 or 316 Stainless steels. It is my understanding that the presents of any halogen (Cl, F, Br, etc.) at any concentration, below say 100F, is a non-issue and somewhere between 150-200F, it becomes a concern. However, I'm not sure at the low concentrations of Cl in city water, that there is an issue, even at elevated temperatures.





RE: SCC of 304/316SS
RE: SCC of 304/316SS
RE: SCC of 304/316SS
The Nalco book says (in part): "When this type of failure was first experienced, it was thought that chloride concentrations as low as 50 - 100 mg/L were responsible. But experience indicates that the concentration of chloride in the water is not the critical factor. The main factor is the existance of conditions that allow chloride cells to develop."
I know of a number of all SS heat exchangers in pool/spa/domestic water service being heated by steam, and they've been in service for years without any problems.
RE: SCC of 304/316SS
Additionally, depending on the size and expereince level of your local water providor, we have seen cases where either maintenence is performed or a pipe is broken and high levels of Cl or other chemicals are added as a response to kill potential bacteria. Though this activity is infrequent and considered negligible in their effects to ss, I have lived in a small rural Illinois town where over-adding was regularily done both because of high maintenence on a failing infrastructure and out of ignorance. The ongoing addition of high concentrations of chemicals caused both copper and ss to suffer due to cummulative effects, especially on hot water lines on small households where water sat for prolonged periods. In this case, though, you have more to fear regarding your health than the nuisance of replacing pipes.
Short answer, if you live in a major metropolitan area, I wouldn't worry.
RE: SCC of 304/316SS
Can someone give me feedback on this question? Greatly appreciated,
rastleman
RE: SCC of 304/316SS
The reason that the chloride level isn't too important is that low concentrations are enough. Excess chloride doesn't speed the cracking.
Temperature is the most important factor.
Galvanic effects between 304 and 316 are rare. As long as they are both passive there will be no problem. If one of them starts to corrode then things will go quickly.
Why are you using stainless? Even though I like it, copper based alloys may be better for what you are doing.
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Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: SCC of 304/316SS
We simply did not consider copper or copper alloys before...
RE: SCC of 304/316SS