Rastelli Raccordi, producer of DIN 2353 – 24°, SAE J 514 – 37° fittings, fittings for flexible tubes, BSP – BSPT – NPT adapters and metric systems, paying utmost attention to the market needs and in the constant research to find the most suitable solutions, has introduced a new eco-compatible system able to increase resistance three times more than standard galvanizing treatments, in other words the alkaline galvanizing plus iridescent passivation and plus film fixing, simply called alkaline galvanizing, which allows satisfying the most demanding applications with no compromise in colouring, too.
We all know the problem of the protection against the metal corrosion where we have been involved since the beginning with the phosphating with brownish colour, afterwards with the passivation with hexavalent chromium of yellow colour that, according to the European regulation dated 18/09/2000 and successive modifications has imposed the use limit starting from 01/07/2007. This has made necessary the research of methods permitting to keep the corrosion resistance degree unchanged, or even to improve it, and therefore someone adopted the nickel zinc of grey and/or black colours while others, like us, preferred the trivalent white galvanization with the addition of passivation and film fixing.
To improve further the protection against corrosion and to protect the intention of Rastelli Raccordi of operating in the full awareness of its environmental responsibility, as well as to obtain a constant colouring, in order to standardize as much as possible the chromatic aspect with what already produced and existing in their own and customers’ stocks, they have decided to adopt the alkaline galvanizing, which is perfectly specular to all that. The alkaline galvanizing treatment is performed by the workshops Rastelli Raccordi at Villanterio (Pavia, Italy), equipped with state-of-art plants that comply with REACH EC 1907/206 and UE CE 30-31 regulations. It is a new bath of cyanide-free alkaline zinc, which allows a more uniform and homogeneous distribution of the zinc layer, with the characteristic of making it more ductile and more resistant to stresses, and a new cobalt-free passivation that uses a nanotechnology of silica particles, in order to obtain a passive layer with much higher thicknesses than common passivations, positively influencing the resistance to white furnaces and tripling the resistance. Finally, the process provides for a sealing with cutting-edge products to protect the passivated layer. The result of the tests in saline mist of the alkaline galvanization treatment, according to ASTM B 117/97 – DIN 50021 SS – UNI ISO 9227 NSS regulations, consists in a resistance to red rust that exceeds 1000 hours and to white rust of more than 500 hours.