Only R.W. Evans & Associates offers truly effective, non-toxic, non-corrosive, and biodegradable cleaning and passivation services. We pioneered the first and best viable chelation chemistries for cleaning/passivation of Pharmaceutical and Biotechnology systems. Our unique and highly effective chelation systems are proven to provide significantly superior results when compared to the mineral acids and "supposed" passive chelants normally used in today's passivation industry.
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MYTH #1
The newer the stainless steel system, the less trouble with corrosion.
FACT
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.
MYTH #2
Corrosion in a stainless system is permanent. Or, even if successfully removed, corrosion will return worse than before.
FACT
Neither case necessarily. Before treating corrosion, you need to determine and eliminate the cause. Often, the fix is simple: resolving bad welds or the replacement of 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 surfaces.
MYTH #3
Passivation is a simple, one-time process that will keep a 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 contaminants (such as heat, tint, and oxides), and ingrained trace contaminants such as aluminum, emanating from the "melt", itself, from recycled sources.
MYTH #4
You can clean and passivate using acid alone.
FACT
Commonly used mineral acid treatments (such as nitric acid) do not commonly attain passivity. In addition, 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. Also, neither acid creates a viable passive film.
MYTH #5
Good passivation can remove all heat tint and oxide 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 #6
Good passivation can resolve metallurgy problems.
FACT
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, such as certain steam traps, etc. further minimize the percentage of (delta/sigma) ferrite content as in castings.
MYTH #7
One chemical application fits all passivation needs.
FACT
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.
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