Myth
Passivation is a simple, one step process that will keep stainless steel system corrosion free.
Fact
Viable and controlled Passivation chemistry is a highly complex process.
Keeping newly Passivated critical systems corrosion free requires pre-application of a multi-step Chelation process to remove dust, debris, abrasive compounds and other surface contaminates (such as heat tint and oxides) and ingrained trace contaminants such as Aluminium, emanating from the “melt”, itself, from recycled sources.
Myth
Corrosion in a stainless steel system is permanent, and even if removed corrosion will return worse than before.
Fact
Neither is necessarily true. Before treating the corrosion the cause needs to be determined and resolved. Often the fix is simple – resolve a bad weld or replace a valve or regulator. Only then should clean-up be attempted using a method affecting “rouge” only. Etchants should never be used as they adversely affect the underlying substrate stainless surface.
Myth
You can clean and passivate using acid alone.
Fact
Commonly used mineral acid treatments (such as nitric acid) do not commonly attain passivity. Not only that they generate hazardous waste and can damage stainless steel substrates.
Citric acid is less hazardous but it is not an effective way to clean stainless steel systems. And, neither acid creates a viable passive film.
Myth
Good Passivation can remove all heat tint and oxides scales from welds.
Fact
Your best insurance is to implement good welding control during the fabrication process. Chemistry cannot correct problems created by plain bad welds and excessive heat tint.
Our procedures, however, provide the best control possible even over marginal welds.
Myth
Good Passivation can resolve metallurgy problems.
Fact
If the metallurgy of a stainless steel system is inconsistent, no amount of chemistry can correct the problem.
Therefore, avoid problems by avoiding dissimilar metallurgy which can lead to galvanic corrosion. Make good choices for system components.
Avoid 400 series items as may be found in certain steam traps etc.
Minimize the percentage of (delta/sigma) ferrite content as in castings.
Myth
The newer the stainless steel system, the less trouble with corrosion.
Fact
To-days stainless steel systems may be formed largely from re-cycled sources. In addition mechanical polishing, electroplating and other common processes add to the impurities impregnating the stainless steel surface and lead to corrosion.
