Ed, you are spot on about the use of process control. We run four passivation lines, and it would be impossible to test for passivation level on the finished product at our production rates.
Were you able to find anything about iron levels?
We don't have any historical data around iron content, and yes, when they look bad the acid is still doing its' job. Our process defines some very specific things, but our Quality Eng. is looking for something they can test to. If you come up with something when you are back in the office, let...
Is there a spec somewhere or a good rule of thumb on how much iron (in ppm) is ok in a 45% Nitric acid passivating bath, before the tank should be purged? I am trying to write an internal company spec and this question has come up.
