Phosphating is a conversion treatment that involves the formation of zinc, manganese, iron or nickel phosphate crystals. This treatment increases the degree of corrosion protection, paint adhesion and reduces the coefficient of friction. It is used as a pre-treatment before painting and for components exposed to very aggressive environmental conditions in the automotive sector, agricultural machinery, industrial plants and household appliances.
In the oil and gas sector, phosphating is applied to OCTG, valves, flanges, bolts and underwater components to increase corrosion resistance, reduce thread seizure and improve the adhesion of protective paints and oils. On OCTG connections, in particular, phosphating is an established practice for lowering the friction coefficient, preventing galling and stabilising the tightening torque on API and premium threads.
The layer is approximately 5–10 µm thick, thin and uniform (≈5–10 µm) and has micro-roughness and porosity that help absorb protective oils. The most common systems for this type of treatment are immersion tank lines and spray tunnels with automatic control, frames for medium-large parts and rotary barrels for small parts, with in-line thickness measurement. The cycle includes degreasing and pickling, followed by immersion or spray application and a phosphating bath, with rinsing and controlled drying.
Ceever designs and manufactures automated, programmable phosphating systems that can be integrated into production management systems.
