RoHS Compliance requirement for Hexavalent Chromium

[NikkiLuna]

We are OEM's whose products are made with galvanized steel and/or galvalum. Our RoHS compliance issue comes from passivization method to chemically treat our steel because Hexavalent Chromium (Cr(VI)) is present in the treat. The RoHS requirement for hexavalent chromium must be less than 0.01% of the substance, by weight, at the raw homogeneous materials level. Per our steel supplier, a 0.2% chemical treatment, which contains Cr(VI), is used to prevent corrosion (white rust) during storage and transit. The product is applied at the mill and becomes trivalent chromium within a few days of production through oxidation. However, the supplier does not guarantee a RoHS compliant product when we receive it. Therefore, for reporting purposes, we are saying we are not RoHS compliant.

We are getting pressure from some of our customers regarding our treatment, and to be completely honest – I’m a little lost. Based on the information that was provided to us, we are lead to believe that the CR(VI) converts to trivalent chromium (CR(III)) within a few days after leaving the mill. Since the steel we use sits for days with the processor, then for days/weeks at our plant before it’s used then for days/weeks in S&R here then at the customers… a month or two has passed. If the chemical only needs a few days to convert and our product sits for a month - is there a concern? Are we RoHS compliant or not? How do we prove it? Is there a test that can be run to determine compliance? Is there an alternative treatment out there that we can use?

 

[Randy]

Have it analyzed to verify either Yes or No

 

[Kales Veggie]

Yes, there is a concern, because Cr (VI) is highly toxic. Are you protecting your workers?

I am not aware the Cr(VI) converts to Cr(III).

1) I would ask for evidence from your supplier that it converts to Cr (III).

2) I would send different aged well prepared sample to a lab

3) I would talk to my supplier and ask for alternatives.

4) Do some research to see if my supplier is correct.

 

[NikkiLuna]

Thanks. This helps alot. One more question (hopefully). Who/what kind of lab do I send samples to for analyzing? Do you know of a reputable lab in Ohio? What do I google?

 

[Kales Veggie]

Thanks. This helps alot. One more question (hopefully). Who/what kind of lab do I send samples to for analyzing? Do you know of a reputable lab in Ohio? What do I google?

I am not familiar with labs in Ohio. A starting point would be Intertek (I am no affiliated with them, but have use them in the past). There are other labs as well, just Google "rohs testing".

 

[JimmyM]

The company I work for purchases parts that have been Nitric 1 passivated which according to the ASTM contains dichromate. If the part is rinsed well after the passivation process, they will more than likely pass outside XRF testing (I am not saying don't get them tested).

Have you considered a Nitric 2 or 3 passivation (according to the ASTM contains no restricted materials) or even a Citric passivation?

I can't remember the ASTM number off the top of my head, but I can get that info when I am at work on Monday so you can google it yourself.

Cheers,
JimmyM

 

[Ray Kremer]

The sodium dichromate in some nitric passivation baths is there to be an oxidizing agent. It does not in any way deposit onto the surface of the stainless. The passive chromium oxide layer on stainless is formed by the reaction between oxygen gas in air and the zero valence chromium on the surface of the steel that has remained after the acid treatment.

RoHS is actually completely irrelevant to stainless steel passivation since RoHS is concerned with coatings and stainless passivation is not a coating, and no amount of the passivation bath remains on the surface.

However, most people don't really get into the details of RoHS and just want a quick yes/no on compliance.

A967 is the ASTM standard you were trying to think of.

However, none of that is relevant to galvanized steel, which is entirely different from stainless steel. I'm not as well versed on galvanized, but you can google on "galvanized steel passivation" for a quick run-down. The result at the American Galvanizers Association is pretty good. You might also be interested in the pdf presentation at ASTM's website titled "RoHS Compliant, Non-Chrome Passivation of Galvanized Steel with Lugalvan Passivation".