Why stainless steel angle is getting rusted ???

Question

I have a problem with a stainless steel fabricated drain cover in a food plant. the end of the angle where it is cut during fabrication is getting rusted when we kept open (ie., outdoor before installing). Is it due to the cutting disc that used by the fabrication workshop? they says once its installed and when the running water splash it , the rust will be gone and never it will come again . is this correct. why the rust only on the cut area

Answer 1

Couple of issues. If they used an abrasive wheel to cut the stainless angle and the wheel had previously been used to cut carbon steel, some of the carbon steel is probably imbedded into the cut.

The rust may go away after all the carbon steel rust away but I doubt it. The only way to get rid of it for good is to grind off the area contaminated by carbon steel. That's what we normally do.

Answer 2

There is a good possibility that they used a cutting disc that had been previously used to cut carbon steel, and has contaminated the stainless. It may take a while for the rust from the deposited carbon steel to go away, I would make them get a clean grinder and clean up their work.

Answer 3

Stainless steel is produced in many different ways. Somtimes companies will market galvanized or coated products as stainless steel. I think that is the case in your situation. Once the metal is cut, the underlying (normal) metal is exposed to the air and will oxidize.

Answer 4

Perhaps your drain cover is made of chrome plated mild steel this would rust if the chrome got damaged.