Passivation of metal with Passivating agents or chemicals is a very important step of complete metal treatment and cleaning.
Passivation is a process by which a stable protective film is formed which fully-conductive and inhibits further dissolution of metal. Passivation also eliminates chances of flash rusting after acidic cleaning of metal. Chemically cleaned or water jacketed boiler and heat exchangers should always be passivated to avoid excessive fouling by iron oxides during service.
A pickling treatment is the only type of post-treatment capable to restore the corrosion resistance of the stainless steel at the weld and other surface damage, to what it was prior to welding. This is true irrespective of the type of stainless steel and there is no difference in effectiveness between immersion in a pickling bath or application of a pickling paste. The corrosion resistance is restored during the pickling treatment because iron dissolves quicker during pickling than other metals, whereby the surface is enriched with chromium and the corrosion resistance of the stainless steel increases. Pickling and passivating this material after processing restores the corrosion-protective oxide layer. We cannot stress the importance of this post-treatment of stainless steel often enough when it comes to preventing various types of corrosion, with all the associated consequences.
Chemtex offers a wide range of passivating chemicals under its registered trade names of ALSTASCALE, PASSIRINSE for:-
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