Stainless steel enjoys a reputation for being ‘invincible’ against rust, but the reality is more nuanced: even stainless steel can corrode under unfavourable conditions. Its resistance derives from a thin passive surface layer which, if damaged or compromised by specific chemical agents, can lose its effectiveness.
In reducing environments or in the presence of concentrated chlorides, stainless steel may develop pitting or crevice corrosion, often more insidious than the uniform rusting of carbon steel. For this reason, the choice of stainless steel grade and any surface treatments must be made according to the actual service environment.
Considering stainless steel as ‘eternal’ can lead to underestimating the need for periodic inspections and proper compatibility with other materials used in the assembly.