How to avoid bacteria traps and crevice corrosion in stainless steel channels
All stainless steels rely on the presence of oxygen to maintain the strong and resilient, protective Chromium Oxide on its surface. If the surface of stainless steel is abraded or scratched, the Chromium Oxide is removed, but in the presence of normal atmospheric oxygen, it will regenerate naturally.
The Chromium Oxide can be instantly repaired or renewed by a process known as passivation. This is where a passivating paste or liquid (generally contains nitric and other oxidising compounds) is applied to the surface.
If the stainless surface lies beneath a crevice, or has been bent over such that oxygen is excluded, corrosion can begin in the absence of oxygen.
Such crevices and air excluding junctions of metal surfaces, will also harbour or trap bacteria which will grow and multiply causing corrosion and odours. The use of silicon based sealants can only buy time during the period that the sealant remains patent and not denatured by sunlight chemicals and sharp objects. It should also be remembered that industrially produced stainless steel products are never manufactured in sterile environments. Therefore, sealants will lock in the bacteria which grow anaerobically (without oxygen).
These problems can be completely avoided by buying well designed product that do not have any crevices or bacteria traps and meet all the requirements of the food and medical industries’ various approval authorities. The simple but clever design of Reef Leveque tile inserts shown below exceeds these requirements.
J. R. WORNER BSc (Metallurgy)