Riboflavin not rinsing after Passivation on 316L 3

It is related to the microscopic surface texture of the 316L.
Mills can supply just about whatever they want to as long as it looks right.
If this material was over-pickled at some point in process, then you stand no chance.
What are your surface finish requirements?
And don't tell me that it is based on Ra as this means nothing in your application.

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P.E. Metallurgy, consulting work welcomed

Is this what you are having a problem with - see slide 5 of presentation

@EdStainless -
I wanted to thank you for your reply. You were right in my ballpark for a suggestion. Thank you for taking the time! I believe you have a great point that this HAS to be the microscopic texture of the 316L. As of the date of my post we have got nowhere. Sending some samples to a lab for material testing is next. BUT, where in the heck and when the heck? No problems in years before this. I did check on the heat #'s for the 1-1/2" and the 1" that this is happening to and the supplier says it's one of their regulars. That doesn't mean it's still not a bad batch or been over pickled. Our surface finish requirements are simply mill finish. I don't know how to better answer that question. I will keep this post updated for the kindness you both (georgeverghese) have shown in taking the time. This is maddening.

@georgeverhese - Thank YOU also for your reply. You had a great suggestion on the Ribo prep and Solubility for coverage testing. We have done this several times with our Ribo to a 'T'. We even tried old Ribo and mixing it long for full dissolve at a slightly higher temperature in case we got a bad batch. So far, same results.

Current update: With the failed sprays, EP has worked with varying results. With new sprays, it appears to be working. The results are somewhat erratic with a couple of the spray devices rinsing quickly and showing no residual as we normally expect and others that show a “ring” at least reacting to the UV light at the neck. At times it is definitely very pale and blue rather than being discernable as green even after several minutes, which would still get flagged as a failure given the current situation. And others definitely show a green ring on the shoulder. As for the next steps, we are giving some samples to a testing lab to do some analysis on the material. This is to see if riboflavin can be confirmed as being present and causing the fluorescence or even the bluish luminescence that we see on some of them. This 'shoulder' is where the Tube welds to the ball top. It seems that the ball, from polishing, has somewhat of an undercut on the weld neck radius on the ball where one of the Ribo rings forms. While this is a polishing issue that can still be corrected, it would appear that the Ribo is still bleeding down TO this holding point.

And on we march. Thanks again to both of you!

@PaulPro
Hi, do you have anymore updates regarding your issue, such as the lab results of the material? I too am experiencing something similar during our commissioning process. Unfortuanately, it seems that there is a diluted stain of riboflavin where there were previous welds. Like you, there are no bright spots of riboflavin present. The tank that had rewelded work on the inner upper ring has been repassivated with no change. I would appreciate any advice at all

Hi KernKraft,
So sorry I didn't get a chance to reply to this several weeks ago. Are you still interested in some updates, or have you figured out some things? Please let me know.

PaulPro said:

Hi KernKraft,
So sorry I didn't get a chance to reply to this several weeks ago. Are you still interested in some updates, or have you figured out some things? Please let me know.

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Hi Paul, no problem. Thank you for getting back to me. I actually thought the issue was resolved after a manual clean but our coverage tests are failing again. So yes, I am very interested in any updates you have.
Thanks again @PaulPro