(211c) Rouging, Passivating and Cleaning of Stainless Steel

Rouging of stainless steel is a problem in many pharmaceutical systems. Usually, there is not a single cause, but a multiplicity of reasons. These include water treatment, chloride content and pH of the product, choice of surface finish on the product and passivation treatment. Cast products have variable passive layers depending on the amount of polishing. Data suggest that rouge formation may be minimized. Rouge can be removed and there are several chemical options that can be used. These treatments can be used not only for rouge removal, but for selective removal of hematite in the presence of magnetite. Proper selection of treatments also allows proper passivation of stainless steel surfaces.