Various types of variability could contribute to or cause spray package corrosion: • Formula ingredient concentration range variability • Variability of contaminant concentrations, such as water • Corrosion inhibitor concentration variability • Package material composition variability • Variability of package component physical attributes, such as valve crimp (clench) dimensions Not determining the effective concentration range for corrosion inhibitors Small concentrations of corrosion inhibitors are often very effective in preventing and controlling package corrosion, and thus enable marketing of corrosive formulas. However, corrosion inhibitors often have an effective concentration range, above which and below which package corrosion occurs. Hence, the effective corrosion inhibitor concentration range should be determined and that range should be part of the manufacturing specifications. Not examining containers from first product runs A corrosion storage test completed after one year has an approximately 7% risk of unexpected corrosion appearing in the commercial products. Consequently, it is advisable to also run a confirmatory storage test on containers from at least the first production of the product. Ideally, confirmatory storage tests would also be conducted on multiple early runs to ensure the effect of variability on package corrosion in the commercial process is known and help lower the risk below 7%. I realize that the best practices for storage tests sometimes strain both limited personnel and storage test facility resources. Hence, my preference and recommendation is for conducting the quicker and more accurate electrochemical corrosion test. Pair O Docs has a state-of-the art electrochemical corrosion testing laboratory. Please contact us if you would like to know more about our faster corrosion testing or to have our Elements of Spray Package Corrosion short course taught at your R&D facility. Visit our updated website www.pairodocspro.com for more information about all the corrosion prevention and control services available from Pair O Docs Professionals L.L.C. Thanks for reading Corrosion Corner and I’ll see you in May. Spray April 2017 Spray 27
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