[TheForge] stainless rust

[Paul]

ries wrote:
> Bruce, you are a scientist, and I am not, but it has not been my  
> empirical experience that stainless steel will spontaneously rust.
> 
> I have seen, and made, a lot of stainless objects that sit outside,  
> for years, and sometimes decades, and do not rust.
> On the other hand, I have seen rust appear in just a few days, where I  
> have scraped a piece with a forklift fork, or imbedded a bit of mild  
> steel mill scale in a piece due to sloppy cleanup practices.
> So I know that contamination from mild steel will cause small rust  
> spots.
> However, I have pieces where I have used something like a 3M pad on a  
> 4 1/2" grinder, and physically removed the rust spot, and then come  
> back 2 years later, and still no rust.
> 
> So its my story, and I am sticking to it, that most rust on stainless  
> is caused by polluting the surface with mild steel inclusions.
more empirical evidence...
My pre retirement employer has been working in the Miller brewery plant 
for 20 some odd years, and has installed miles of SS piping and vessels 
and duct work. The atmosphere in a brewery is laden with cleaning 
solutions, moisture and steam vapors. No rust on the piping. What can 
rust stainless is, as ries mentioned, contaminated brushes, tools and 
cleaning procedures. But even then it is surface rust and can be 
removed. Mostly it is prevented but not even buying any wire wheels or 
wire brushes made of anything other than SS

paul

jadap/retired after all...