What is passivation in stainless steel hose reels?Posted by Coxreels on Feb 27, 2018
To begin answering this question, let’s take a deeper look at what stainless steel is comprised of. While stainless steels are naturally corrosion-resistant, they are not entirely protected from corrosion. Stainless steel derives its corrosion resistant properties from its chromium content. The chromium, in the presence of air (oxygen), forms a thin film of chromium oxide which covers the surface of the stainless steel. Chromium oxide and chromium in the material gives stainless steel its corrosion resistant properties.
Under completely ideal situations, pure stainless steel forms an oxide film when exposed to oxygen in the atmosphere, which ultimately protects the stainless steel from corrosion. Under realistic conditions, such as most factory settings, foreign material in a manufacturing environment may be transferred to the surface of the stainless steel parts of your hose reel, often inhibiting the formation of the protectant oxide. These contaminants need to be eliminated from the stainless steel and the removal process is known as passivation.
Stainless steel passivation is a process that chemically removes these natural contaminants and forms a “passive” oxide film layer, which further improves corrosion resistance. This process proves especially beneficial for your stainless steel reels in unforgiving environments, such as those in very close proximity to saltwater.
Passivating stainless steel is typically accomplished by dipping the part in a bath of nitric acid. Nitric acid dissolves any free iron or other contaminants from the surface, which cleans the metal, and it re-oxidizes the chromium, and restores the original corrosion-resistant surface to the part.
Anytime a system is being fabricated, there is the possibility that residues from the fabrication process end up in the system components. Extreme care must be taken to prevent the stainless steel particles from getting into the system during construction. Stainless steel passivation will create the most effective corrosion resistance surface for your hose reel.
Properly passivized stainless steel reels will increase the life of expensive chemical fluid transfer and wash down hoses, and the life of the reel in itself.