Stainless Steel Pickling – The removal of soluble surface oxides, silicon based sands and ceramics, and surface based free iron from 18-8 stainless steel alloys. This is accomplished by soaking the parts in a bath containing parts of nitric and hydrofluoric acid mixed with water for a period of time sufficient to remove the surface impurities. The bath is typically heated to speed the process. Pickling will also passivate the surface.
Purpose – Pickling stainless steel will remove soluble scale, casting sand and ceramic residue, and weld heat tint discoloration from the surface of stainless steel parts. It also allows the formation of a passive invisible oxide surface that gives stainless steel its ability to be corrosion resistant.
Process Description – Parts are put into baskets of stainless steel and immersed in a bath of nitric and hydrofluoric acids with water for a period of time sufficient to remove surface impurities. The bath is heated to speed up the process. The parts are then removed from the bath and thoroughly rinsed and dried.
Operational Standards – We operate our process to the following standards:
- ASTM A380 – Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and, Systems.
- Customer specific standards – When ASTM standards are not acceptable.