The authoritative public forum
  for Metal Finishing since 1989
  

  -----

No Oxidation Inox 304/316 Warranty Certification

I'm an illumination mast manufacturer for some time using inox 304 or inox 316. Of course I'm using the same machinery for forming carbon steel. I understand that after machining (welding, forming, assembling, etc.) a passivation operation is necessary. Will this treatment guarantee the complete no oxidation security? Can I safely give the timely no oxidation certificate ? Must be regarded that urine from animals as (Dogs, Cats, and others, steel from chains tight to the mast, glued posters) may occur. Can I give the certificate excluding this inconvenience?

Domenc Trullas Ill
- Manresa Barcelona Spain
2001

If I understand, you are only forming posts, and need to give some warranty to the customer that they will stay shiny and free of rusty discoloration? If so, be forewarned that ANY time a mild steel like strapping, chain or wire is in contact with 304/316 stainless in presence of water, especially acid rain, rust discoloration will occur at the contact point. (If you have any SS scrap in a steel drum, outside where rainwater collects, take a look at the scrap where it touches the drum sides, for an example of what can happen.)

Thinking about animal (or human) urine, I would not expect it to cause corrosion staining on SS, unless mild steel is also wet, and in contact. The post should be getting continually washed down by rain, too, which helps.

The bottom line is: caution the customer that the product will stay shiny only if ... and state the precautions.

W. Carl Erickson
- Rome, New York
2001