Passivating to QQ-P-35 and disposing of chemicals

[jeffg35]

We are a CNC Machining facility and would like to setup a passivating line for our stainless steel parts to supply our customers with turnkey parts. They are requiring QQ-P-35 specification. We would like to know the details of the different tanks you need, there contents, and the processing steps. We also would like to know how you dispose of the nitric acid and the sodium dicromate so we meet enviromental regulations. If you would like to just give me a short note with a contact name and phone number, we could contact you to talk further on our specific requirements.

Thank You

 

[kenvlach]

Passivation is a relatively simple process. Depending upon your location, meeting environmental requirements for secondary containment and wastewater treatment will cost at least as much as the tanks in your process line. Secondary containment is needed for chemical storage, processing and wastewater treatment areas. A hazardous materials permit, a hazardous waste generator account, hazardous waste worker training and a wastewater treatment permit are required in the US. If large enough quantities of hazardous chemicals are on-site, additional requirements kick in (emergency contingency plans), and you may be subject to TRI reporting since the EPA considers neutralization of nitric acid to be a chemical manufacturing process (nitrates are formed).
Where are you located?

A process line could be as follows (+R is rinsing in counterflowing tapwater):
Descale as necessary (if heat treat, welding or casting scale) +R+R.
Electroclean+R+R to a water break-free surface
Passivate (in Nitric acid solution)+R+R
or Passivate (in nitric acid + sodium dichromate)+ dragout rinse+dragout rinse+R
Hot DI water rinse
Air dry
Inspection and packaging.

If you haven’t already done so, download QQ-P-35C from the ASSIST site:

http://assist2.daps.dla.mil/quicksearch/

It gives the passivation solutions, temperatures and times.

For general information on pretreatment (cleaning, rinsing, descaling if heat treated parts), chemical resistant tanks, plant engineering and wastewater treatment (including Cr⁺⁶ reduction), see

http://www.metalfinishing.com/WZ/MetalFinishing/guidebooks/show/

For a small setup doing batch treatment of Cr⁺⁶ wastewater, I recommend using sodium hydrosulfite; see

http://www.finishing.com/202/34.html

Also, go to the

http://www.finishing.com

website, read the Passivation FAQs and search for letters re passivation and chromium reduction.

 

[jeffg35]

We are located in New york State.