4 Facts About The Passivation Procedure For Stainless Steel Pipes

Passivation is one of the primary treatment processes for stainless steel pipes. Passivation can improve durability, longevity, and resistance to corrosion.

In this article, we’ll look at four important facts about passivation, and why it should be part of your routine preventative maintenance schedule for stainless steel pipes.

1. Prevents Oxidation And Corrosion

Stainless steel is naturally resistant to corrosion and oxidation, but this comes from the qualities of the surface of the metal. The shiny, stainless appearance of stainless steel comes from its increased chrome to iron ratio, which provides a stable and inert oxide layer that prevents oxidation and corrosion. This can deplete over time as iron particles accumulate on the surface, which can catalyse corrosion if left untreated. The passivation procedure for stainless steel pipes increases this chrome iron ratio on the metal surface, which allows a chromium oxide (Cr203) layer to spontaneously emerge as the metal is exposed to oxygen in the atmosphere. This layer protects the underlying surface from further oxidation or corrosion.

2. Ideal For High-Purity Environments

The acids and chemicals used in many surface treatment procedures make them unsuitable for high-purity environments, such as the medical and pharmaceutical industries, where the need to maintain a sterile condition is essential. Passivation is ideal for these sectors due to the specialised equipment and proprietary chemical blends used in many passivation processes. Passivation removes a variety of contaminants from stainless steel surfaces, including iron contaminants (usually through a citric acid solution), but also organic residues and particulate matter. The surfaces are thoroughly rinsed, dried, and inspected for purity following the procedure.

3. Does Not Damage The Surface

Pickling and passivation are the two main treatment procedures for stainless steel equipment. Unlike pickling, however, passivation doesn’t risk damaging the surface finish of your stainless steel. The strong acids used in pickling, such as hydrofluoric and nitric acid, remove a thin layer of the metal surface, alongside any scale, rust, and discolouration. This is an aggressive process that etches the surface and reduces the durability of the metal. Instead, passivation removes lightly adhered contaminants, leaving the underlying metal untouched, and helps to restore the protective chromium oxide layer, minimising the need for re-cleaning and avoiding manual methods that could scratch or damage the surface.

4. ASME Compliant

Passivation adheres to the ASME (American Society of Mechanical Engineers) BPE guidelines for bioprocessing equipment, which specify standards for not just demonstrable overall cleanliness, but also the ways in which cleaning solutions can effectively reach their target surfaces. Compliance with ASME BPE – which, despite originating in the USA, is widely recognised internationally – guarantees that your systems are maintained to the highest industry standards.

Next Steps

To find out more about passivation and how it can support hygiene in your facility, promote compliance, and enhance the longevity and performance of your stainless steel equipment, please contact our team today for expert advice.