Immersion pickling consists in placing processed steel in hydrofluoric and nitric acid. This method, thanks to the application of bath with the dimensions of 7000x2000x1500 mm enables uniform surface treatment of long sections of pipelines, manifolds, tanks, etc. Spray pickling is used in case of necessity of chemical treatment of places difficult to access. Nitric acid is used for passivation of steel. Such treatment increases the passive layer of stainless steel. Passive layer reduces steel oxidation, and therefore improves corrosion resistance. Not only does pickling technology influence the quality of manufactured products, but it also improves the aesthethic properties by removing discolourations caused by a high welding temperature.