Chemical passivation is not always necessary, but is important where surfaces are possibly starved of oxygen, for example in the case of pipework or enclosed vessels. Where items are pickled and likely to be exposed to corrosive atmospheres, such as chemical processing plants or marine and coastal locations, chemical passivation following pickling is highly recommended. Additional passivation following electropolishing is not necessary due to the excellent oxide layer formation present after electropolishing.
Pickling and passivation of stainless steel is not restricted to immersion in treatment tanks, although this method is widely used. Where fabrications are too large for immersion or require treatment in-situ, spray-on systems can be employed. The results are indistinguishable from the finish obtained by immersion methods. Where only localised areas require treatment, for example heat effected surfaces resulting from welding, paste products can be applied with a brush.
ANOPOL has extensive pickling and passivating facilities at its Birmingham and Bordon, Hampshire facilities. Additionally, ANOPOL can supply all the necessary equipment, including water treatment, together with the necessary chemicals, to those companies wishing to carry out their own pickling and passivation.
Cleaning, pickling and passivating products are available in liquid and paste form. ANOPOL also markets the WELDKLEEN machine, an environmentally friendly way of removing weld burn.