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SS 304 or SS 316 for the purified storage tank in the R.O. plant

Dear Sirs,

I would like to know the exact difference and the risk if we have designed the final storage tank or the purified storage tank with stainless steel 304 polished, because we will use the its water which will be hot once a week for sanitization purpose for all the plant.
and if I use the same purified water but it will be exposed through a heat exchanger which has the same material ss 304 to a steam is there any possibilities to have a corrosion or it will be safe more than 316.

please advice me

Mohamed Roushdy
mechanical engineer - Egypt
February 9, 2009

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February 10, 2009

316 will always be more resistant to corrosion than 304. We cannot tell if 304 would be adequate in your particular case, or if you need 316.

If your plant is to be fabricated by welding, then you should use the "L" grade of whichever stainless grade you decide on. That is, use 304L instead of 304, or 316L instead of 316. You will then not have substantially reduced corrosion resistance near the welds.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.