Sulfamic acid cleaning of Hastelloy C-2000? 1

[ehbadger]

Does anyone have experience with using sulfamic acid to clean C-2000 equipment?

I've found literature for C-276 in 10% sulfamic (0.002 mils/yr) but nothing for C-2000. My main concerns stems from the Copper in C-2000. Our contractor acid cleaners use sulfamic but have a note in their documents: "Sulfamic acid is not an acceptable solvent for use in systems whose materials of construction include copper or copper alloys, because of the possibility of stress corrosion cracking.". Haynes shows C-2000 composition at 1.6%wt Cu. Any concerns with cleaning a C-2000 vessel with sulfamic? Or any recommendations on literature that would help me understand the SCC concerns specific to the copper? Thanks

 

[EdStainless]

That amount of Cu is not an issue. At these levels it is all in solution and SCC from sulfamic is not an problem.

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P.E. Metallurgy, Plymouth Tube

 

[ehbadger]

Thanks EdStainless! This is in line with what I've found elsewhere. In case anyone else has this question in the future; we spoke with a Haynes (manufacturer of C-2000) metallurgist, his response was (paraphrased):

"Copper is a substitutional atom for the Nickel so it’s part of the crystal matrix and not present as a precipitate or secondary phase. If anything, I would expect the C-2000 to be slightly more resistant to Sulfamic than C-276."

 

[Guest102023]

I can confirm EdS's advice, having looked at this issue in depth a couple of years back.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"