Water Softener Material of Construction

[dogbertcountry2]

I have heard a few diffenrent opinions about the subject. We had a Carbon steel with epoxy coating tank with PVC internals and outlet piping. New construction is 304 SS tank - we have just had a failure within less than one year.

We use a sodium chloride brine solution to regenrate the beds. There is no condensate recovery. The water is ambient temperature. The vendor had assured us that chloride stress cracking was not an issue.

Any opinions?

 

[Goahead]

The regular procedure would be to perform a metallurgical investigation of the failure to understand the possible causes.

http://www.welding-advisers.com/

 

[moltenmetal]

Your post isn't clear. What failed: the 304SS tank, or the epoxy-lined CS tank?

I've seen lots of rubber-lined CS for tanks like this.

 

[dogbertcountry2]

The 304 SS failed. I was trying to understand if using SS is a no-no in softener service. Furthermore, waht role in that determination, is attributable to NaCl brine?

 

[yank38]

SS does not like sodium. Use potassium chloride for regeneration and your problem should go away.

 

[cub3bead]

Actually the 304 does not like the Cl. Switching to KCl will have the same outcome with 304 as the NaCl. The Cl causes pitting and stress corrosion cracking. 316 won't help much either.

Your choices are epoxy or PVC lined CS or FRP (some say GRP). Rubber lined CS is a good choice but not the most economical.

 

[bimr]

What do you mean by "condensate recovery"? What type of failure are you talking about?

cub3bead has made some good suggestions. I would add that you can get by with just a steel tank without tank lining since the brining step only occurs for a short period of time.