Are there any halides in the solution? (even single digit ppm)
are there any oxidizing ions? (O, NO3–, Cr2O7–2, MnO4–, Fe+3, Cu+2)
Without these then a high alloy stainless (6%Mo) should be fine.
With them you need some special help.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube