To have their optimum corrosion resistance, stainless steel surface must be clean and have an adequate supply of oxygen to maintain their passive surface layer.
Rust staining can occur and has been reported as anything from a slight brown ‘bloom’ on the surface to severe surface pitting or rusty scour marks on items such as handrails. These effects are usually due to surface contamination from contact with non-stainless steel items.
Iron contamination can be costly to remedy, and is avoidable. These issues have been well documented and most publications on stainless steel deal with the problem.
Avoid contamination during all storage, handling and fabrication stages and also during the service life of the stainless steel item.
If contamination is suspected then test the surface.
Where contamination is detected take steps to remove it all and avoid spreading it around during the removal operation.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)