what is the impact of chlorides in ss304 pipes and vessels, what is the tolerance limit of chlorides forss304?

Question

what is the impact of chlorides in ss304 pipes and vessels, what is the tolerence limit of chlorides for ss304.which temperature it will affect more. how we remove chlorides otherthan r o process

Answer 1

One of the most important forms of stress corrosion that concerns the SS304 is chloride stress corrosion. Chloride stress corrosion is a type of intergranular corrosion and occurs in austenitic stainless steel under tensile stress in the presence of oxygen, chloride ions, and high temperature. It is thought to start with chromium carbide deposits along grain boundaries that leave the metal open to corrosion. This form of corrosion is controlled by maintaining low chloride ion and oxygen content in the environment and use of low carbon steels.
http://www.corrosion-doctors.org/Forms/scc.htm
http://72.30.186.56/search/cache?ei=UTF-8&fr=slv1-msgr&p=STRESS+CORROSION+CRACKING-SS304-CHLORIDE&u=public.lanl.gov/MCEL/PDF-Publications/SS304.PDF&w=stress+corrosion+cracking+ss304+chloride&d=S490IUVuN0pi&icp=1&.intl=in

EVEN IF YOU hold the water in ss304 pipe line / vessel for a longer period than there are chances of failure of the same due chloride presence in the water.
pitting type corrosion may occured due to chloride attack.(local pitting)

We were relieved from this SCC BY changing the MOC of heat exchanger from ss304 to ss316 Ti grade.
At present we are using DAUPLEX STEEL and since last 4 year no tube leak is observed.

Corrosion is directly proportional to temperature,velocity,pressure/vaccume.

Answer 2

I have found through my expereince that this mostly depends on temperature. The lower the temperature, the longer the lifespan of the materials. You would have to check this against some test results which should be available from your mill supplier of the raw SS material. 316 SS is only good for 200 degrees before chloride grain boundary corrosion sets in. 304 is a little better and it may be good up to 250 (but again, please check cause I'm working from memory). At 400 degrees, the material lasts a reltviely short time even with chlorides in the parts per million range (I'm talking a matter of weeks- not months or years). We had an application at 700 degrees and ended up going with Incolloy- which is much more expensive but still cheaper than repeated failures or an RO system.

Answer 3

Not good at all. What chloride are you looking at? Inorganic salts (like NaCl, NH4Cl, etc) will crack the hell out of SS304. Use atleast SS 316, better still SS310 and Titanium is the best.

Answer 4

Chlorides attack 304 SS. Even at low concentrations it can be a problem. Avoid using SS for chlorides need to use another alloy or plastic.

I don't have a chart handy but I think it's carpenter 20 alloy that is the most economical if you can't use plastic.