The pickling and passivation processes of stainless steel are often considered as one: pickling removes the oxides from welds while with passivation the original condition of stainless steel is recovered.
Pickling is the process carried out in a chemical bath, which is performed in a tank with HN03 nitric and HF fluoride solution. Pickling can be a pre-treatment or a finish treatment.
In the case of pre-treatment, the immersion will last the time necessary for the elimination of oxides and impurities deriving from the various treatments undergone during processing (e.g. cutting and welding). Subsequently the part can be sent to the electropolishing line to give it both the brilliant physical appearance typical of stainless steel and corrosion resistant.
To carry out this type of process the parts to be treated are handled with extreme care and plastic materials are used to separate the pieces to avoid scratches: as working in bulk quantities, the small items can become stained and with an uneven finish.
The subsequent pressure washes, passivation and final washing in demineralized water allow to get a finished product that is aesthetically pleasing and resistant to corrosion.
The solution that Clerici SRL uses is particularly suitable for the 304 and 316 series. The parts to be treated can also be subject to pickling prior to a micropalled finish with stainless steel balls in order to smoothen even more any signs of processing such as grinding that with the pickling process would not be covered.
Clerici SRL is equipped with a new pickling line system with a large tank and tanks for degreasing, passivation and washing in demineralized water.
This type of solution requires compliance with both the environmental and safety regulations, and Clerici SRL works and is in accordance with all of the requirements.
All our pickling processes comply with the American regulation ASTM A380-06 “Standard practice for cleaning, descaling and passivation of stainless steel parts, equipment and systems”.