James: Your question is difficult to answer. You are interested in a corrosion rate across a wide spectrum of temperatures. At 2% concentration and 140F, 316SS should be ok. At 2% at 500F, you should expect either or both excessive uniform corrosion or caustic SCC. Another issue is if and when the caustic gets reacted to extension in a batch reaction process or is constant throughout the process cycle. There is an abundance of information regarding the corrosion characteristics of caustic with metals and alloys. Typically, as with your needs, one has to "dig" for it. We have additional information regarding caustic on our website at http://hghouston.com/naoh.html. Hope this helps! David Hendrix The Hendrix Group Inc.