Pure Water Corrosion
Pure Water Corrosion
(OP)
I have an RO (Reverse Osmosis) skid that will be installed to treat boiler feed water. The water after this treatment skid will be deiozized with a PH of about 5 - 6. What are my piping material options for this service? Is there a threshold for the percentage of deionization were carbon steel can be used?





RE: Pure Water Corrosion
RE: Pure Water Corrosion
RE: Pure Water Corrosion
Your pH seems low, is this normal for this service?
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RE: Pure Water Corrosion
Is this water that's been deionized but not yet deoxygenated? If so, 316L SS will be fine, provided you insulate and keep chloride away from the surface to mitigate the external CSCC risk EdStainless talks about. Don't forget about the chloride in the insulation...
If it's been deoxygenated and the inhibitors added, carbon steel will either be fine, or your boiler won't be!
RE: Pure Water Corrosion
RE: Pure Water Corrosion
If it is DI, but not deox, then I would still use 2205. It will not cost more than 316L and it will offer CSCC resistance.
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Rust never sleeps
Neither should your protection
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RE: Pure Water Corrosion
RE: Pure Water Corrosion
You are looking at using lighter wall in 2205 right? The yield strength is double that of 316L. It is so much stronger, more resistant to pitting and crevice corrosion, and it has useful resistance to CSCC.
I would still use 316L for the the valves and instruments.
I have seen many systems installed in welded 2205 and there is no basis for saying that it is more difficult to weld.
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Rust never sleeps
Neither should your protection
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RE: Pure Water Corrosion
RE: Pure Water Corrosion
In comparison, welding 316L is childsplay.
I'm not saying that the OP shouldn't use 2205 for their application- frankly we still don't have enough detail from them to give them an accurate selection- I'm just pointing out an issue we've experienced with the material. Certainly if you can get away with 316 for the valves etc. the cost impact of using 2205 for the piping would be moderated a fair bit.