Experiencing stress corrosion cracks in stainless steel water lines

[jktwn]

We are experiencing severe problems w/ corrosion stress cracks in 1/2" stainless steel flex hoses that supply cooling water to heat/cool jackets on our plastic extrusion lines. The RO water system is a closed loop with make-up that passes through SS coils embedded in a cast aluminum heater jacket (230C) then through a heat exchanger and pump.

The RO water sample shows conductivity of 750 micro mho and chloride concentration of 236ppm. I am not proficient in this field and would like to ask for comments and suggestions. This is a big problem for us right now.

The problem seems to have begun about 90 days ago following a RO water supply contamination incident.

 

[MJCronin]

wx,

I have little experience in this area, but I feel that your chlorides are too high.

Many major chemical companies hydro test stainless steel tanks and heat exchangers with water that has chlorides held to less that 50 ppm. 236 sound too high.

At what temperature does your system run ?

304SS or 316 ??

Try

http://www.hghouston.com

(David hendrix) for another corrosion forum.

Good Luck !!


MJC

 

[jktwn]

Thanks for the reply. I will check the forum you suggest for additional info.

more info...
The 1/2" flex lines are 321SS with 316SS ends. The braid is 304SS (this is according to the vendor - I have not confirmed materials). SCC is most evident at the welded end connections with pitting and minor SCC along the length of the 321 lines.

The RO water temperature varies from about 40C on the lines feeding the heaters to about 200C on the outlet side. Our city water normal chloride concentration is 30-40 ppm.