Stainless steel in cooling water and sodium hypochlorite 1

[StoneCold]

Hello all
I have been reading around here for a couple of hours and can not get my head around this issue.
I have reactor jackets made of 304L stainless. They are used for steam and for cooling water.
My cooling water treatment guy, would like to switch my biocide to sodium hypochlorite, to a level of about 5 ppm of free chlorine.
While I know I want to limit my CHLORIDE exposure on my stainless to less than 100 ppm, how can I determine the chloride concentration that my stainless steel sees by just controling the free chlorine?
Or am I confusing the whole issue and I only care about free chlorine?

What if I was feeding chlorine dioxide? What type of chlorine would I be worried about then?

Can you point me in the right direction on this or tell me a specific article to read?

Thanks
StoneCold

 

[metengr]

http://www.es2inc.com/wp-content/up...mistry-for-Water-and-Wastewater-Treatment.pdf

 

[EdStainless]

Does he want 5ppm free Cl continuous?
That is a lot. I see that level in burst treatment (2 hr/day).
In continuous treatment I rarely see anything over 1ppm.

There is no fixed relationship. You can have your 5ppm with 10ppm total chloride or with 100,000ppm total. It depends on other ionic species in the water.
It is the total Cl that will drive pitting attack.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[StoneCold]

Thanks metengr and EdStainless.
I read the article that metengr posted and now I see what you are saying Ed about the total chloride content.
With large biological loading you could have extremely large amounts of chloride floating around. I think we will have to watch the lbs of chloride fed per day and the holding time to get a rough handle on it and some ICP testing to back it up.
Ed I could be mistaken about 5ppm he might have said 0.5ppm. I will have to check.

Thanks for the help on this.

Regards
Brad Stone

 

[SJones]

The chlorine will exist as either hypochlorite or hypochlorous acid dependent upon pH. There will also be a reaction with organic compounds and any ammonia. What is left over is the free available chlorine (FAC). The reaction with iron would generate chloride ions. 304 will readily undergo pitting and crevice corrosion at FAC levels 2 < x <5 ppm but seems to be resistant at 20 - 25 ppm FAC (NACE Corrosion 98, Paper 98708)

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04