Hot KOH and SS 316 or SAF 2205: SSC?
Hot KOH and SS 316 or SAF 2205: SSC?
(OP)
Any experience on stress corrosion cracking in SS 316 used for hot (80 C) potassium hydroxide (KOH) with presence of oxygen? We have had some cases of severe problems, while other systems with (seemingly) identical service are doing fine. Our chosen replacement material in problem areas is SAF 2205 - any comments?





RE: Hot KOH and SS 316 or SAF 2205: SSC?
316 is very touchy in hot caustic service. Your experience isn't uncommon.
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Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: Hot KOH and SS 316 or SAF 2205: SSC?
What is your KOH concentration? Depending on concentration, you could be forced to upgrade even further to a Nickel base alloy - Nickel 200, Inconel 625 for handling concentrated caustic solutions.
RE: Hot KOH and SS 316 or SAF 2205: SSC?
= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: Hot KOH and SS 316 or SAF 2205: SSC?
In any case, duplex stainless steels should be an improvement. If for some reason you decide to use a ferritic stainless, I would suggest that you use a 26Cr grade, such as E-Brite. E-brite is still produced, but it may be difficult to get in all of the sizes and product forms you require. I do not think you will get adequate resistance from the conventional 12Cr or 17Cr grades.
Additional reference material can be found in books by Paul Dillon and published by the Materials Technology Institute (MTI):
"Materials Selection for the Chemical Process Industries"
"Corrosion control in the Chemical Process Industries"
Also Volume 13 of the "Metals Handbook," published by the American Society for Materials - International has usedful information.
If you need more specific information, I suggest you contact the Nickel Institute in Toronto (http://www.nickelinstitute.org