After dealing with a leak from a 73 kg compressed chlorine gas cylinder at 6 bar, there was green powder/rust/discoloration on the stainless steel tubing similar to copper chloride or copper sulphate. Any thoughts of what this might be?

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    $\begingroup$ It is likely to be compounds of the main elements in stainless steel: Ni, Cr and Fe. Special alloys are often used when corrosive gas exposure is expected, e.g., Monel. In your case, the exposure was accidental. $\endgroup$ – Ed V Jul 2 '19 at 19:50
  • $\begingroup$ Thanks Ed V , but would any of these have the chractrustic blue/green of Copper Chloride/sulphate ? $\endgroup$ – Roy Jul 2 '19 at 20:35
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    $\begingroup$ All three of the metals have some green compounds. There are numerous varieties of stainless steels, e.g., 316 and 304, but I don’t know what stainless steel you are dealing with. I will check to see if I can find the colors of the chlorides of Ni, Cr, and Fe. But I am guessing someone here will post an actual helpful answer. If I find anything useful, I will post as a comment. If an actual helpful answer is posted by someone, I will delete my comments: I think (I am still new here) that comments are supposed to go away sooner rather than later. $\endgroup$ – Ed V Jul 2 '19 at 20:49
  • $\begingroup$ BTW, some stainless steels that are resistant to dry chlorine are attacked by moist Cl2, so check for any water in the environment. $\endgroup$ – DrMoishe Pippik Jul 2 '19 at 21:03
  • $\begingroup$ From wiki, the hydrated chlorides are various greens. Also, wiki says HCl attacks all varieties of stainless steel and contact should be avoided. I know this is correct from my lab experience. When chlorine gas encounters water vapor in the air, some HCl gas is formed, so I think you have some hydrated chlorides. Hope this helps! $\endgroup$ – Ed V Jul 2 '19 at 21:03

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