Potassium Iodide compatability with S/Steel or Brass 1

[cpretty]

Hi all,

Has anyone had any experience with KI (5.5g/kg solution) with Brass or S/Steel. I searched for ages on the net, but can only find minimal info.

ANy suggestions of where to look next would be appreciated.

Craig

 

[25362]

Craig, you are right, it is difficult to find the information you want in the internet. However, if you make a mental switch to another, a bit more aggressive, salt: LiBr, you may find quite a lot of information on the net by looking for corrosion in absorption refrigeration units based on water/lithium bromide solutions. I hope this idea is of value.

 

[TEV]

Sedriks (Corrosion of Stainless Steels) references a report that Iodides can cause piiting corrosion in stainless steels similar to that observed and extensively reported for Chlorides. The report is by Marchlewska an Szklarska-Smialowska in Proceedings of the 8th International Congress on Metallic Corrosion, Mainz, Germany, Sept. 1981. I do not have access to this report

 

[rolledalloy]

There is little data available in iodide salts. In general they would likely act similar to other halides salts such as chlorides (plenty of data), bromides, or fluorides.

As such likely one would find increasing resistance as moly increases in the stainless steels and nickel alloys. From least to most resistant. 304, 316L (2% Mo), 2205 (3% Mo), AL-6XN (6% Mo), C-276 (15-16% Mo).

Carpenter Technology publishes a bulletin on their Carpenter 20Cb-3 alloy that contains corrosion data on lots of materials in various solutions including potassium chloride and potassium bromide. Since we offer that material you could request it from

http://www.rolledalloys.com,

but I would not suggest Carpenter 20Cb-3 for this service.

 

[saxon]

cpretty, When application data is sparse or non-existent, get empirical. Set yourself up a corrosion test rack with the various alloys in question and run a corrosion test at the temp the process runs at. For info on how to set one up, see Perry's Chemical Engineers Handbook.

saxon

 

[cpretty]

Thanks for the replies.

I am glad that other people agree that it is hard to find information. Pitting corrosion was what I suspected would occur, and issues with crevice corrosion possibly.

Interesting that no-one has mentioned brass. Further research has sugested that de-zincification could be an issue, which makes me wonder why some of the valves on a current test rig are made of brass.

Thanks all.

Craig