Passiverede

Passiverede is a term used in Danish and Norwegian to describe metal surfaces that have undergone passivation. Passivation is a chemical treatment applied to metals, most commonly stainless steel, aluminum, and titanium, to form a thin, protective oxide layer on the surface. This oxide layer, typically consisting of chromium oxide on stainless steel, reduces the metal’s reactivity and increases its resistance to corrosion and chemical attack.

The process generally involves cleaning the surface to remove oils, scale, and contaminants, followed by a passivation step that uses an oxidizing solution. Common agents include nitric acid or citric acid, sometimes with variations in concentration and temperature. The goal is to dissolve away free iron and other soluble impurities that can promote corrosion, leaving a stable, passive oxide film that slows further oxidation.

Passivated surfaces are important in industries where corrosion resistance is critical, such as food processing, pharmaceuticals, medical devices, chemical processing, and construction of piping and equipment. Passiverede indicates that the surface has been treated and meets a specified level of passivity, although it is not a coating or plating; the protection arises from a natural oxide layer rather than an additional layer applied to the surface.

Quality assurance for passivation often involves visual inspection and surface testing to assess the removal of free iron and the integrity of the passive film. Procedures and acceptance criteria can vary by industry and region, with some standards recommending specific acids, temperatures, and immersion times to achieve the desired corrosion resistance.