Passivation Myths

The newer the stainless steel system, the less trouble with corrosion.

• Today’s stainless steel systems are formed largely from recycled sources of lower alloys. In addition, mechanical polishing, electroplating, welding, and other common processes add to the impurities impregnating stainless steel surfaces and leading to corrosion.

Corrosion in a stainless system is permanent. Or, even if successfully removed, the material will be more prone to corrosion in the future.

• It is very possible that neither of these things are true. Before treating corrosion, you need to determine and eliminate the cause. Often, the fix is simply resolving bad welds or the replacement of a valve regulator. Only then should cleanup be attempted using a method affecting ‘rouge’ only. Ethants should never be used as they adversely affect the underlying substrate stainless surfaces.

Passivation is a simple, one-time process that will keep stainless steel systems corrosion free.

• 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 contaminants (such as heat tint and oxides); and ingrained trace contaminants such as aluminum, emanating from the “melt”, itself, from recycled sources.

You can clean and passivate using acid alone.

• 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 systems. And, neither acid creates a viable passive film.

Good passivation can remove all heat tint and oxide from welds.

• 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.

Good passivation can resolve metallurgy problems.

• If the metallurgy of a stainless 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 certain steam traps, etc. Further minimize the percentage of (delta/sigma) ferrite content as in castings.

One chemical application fits all passivation needs.

• Because no two stainless steel systems are exactly alike, chelation chemistry must be designed on an individual basis to encompass a divergent series of encountered conditions. Beware of “cookbook” chemistry that promises quick results.