laminated aluminum foil packaging, such as bag-on-valve (BOV) packages. However, preliminary data suggests that the zerotime (or no corrosion data) risks for these types of packages are approximately 43% for PET-coated TFS and 20% for BOV-types of packages. The two points below the storage test curve in Figure 1 are correlations for electrochemical corrosion tests on multiple types of uncoated spray packages, coated spray packages and laminatedfoil spray packages. There are two correlation points instead of two curves because electrochemical corrosion test lengths are significantly shorter than a corresponding storage test. Correlations were calculated between predictions from electrochemical tests and their corresponding actual commercial package corrosion. The correlations are empirical estimations for the probabilities of localized metal and coating/laminate film corrosion in spray packages. They were obtained from: • uncoated tinplated steel aerosol containers (ETP) • all types of epoxy coatings on ETP aerosol containers • epoxy, Polyamide-imide (PAM) and coated aluminum aerosol containers • all types of epoxy coatings on tin-free-steel (TFS) aerosol containers • PET-coated TFS aerosol containers • Laminated foil BOV packages Approximately 7,500 traditional aerosol containers were used to generate the Storage test curve in Figure 1. Data from over 12,800 spray packages were used to generate the two electrochemical corrosion test correlations in Figure 1. The square is the electrochemical test correlation for uncoated spray packages and the diamond is the correlation for coated and laminated-foil coated spray packaging. I will complete this discussion in the February edition of Corrosion Corner. In that issue, I’ll discuss how to read the curve and correlations in Figure 1, plus the limitations associated with storage corrosion tests and electrochemical corrosion tests. We would be happy to teach our Elements of Spray Package (Aerosol Container) Corrosion short course, which provides a more comprehensive discussion on spray package corrosion science and technology, corrosion prevention and control, at your R&D facility. We have also introduced the Corrosion Partnership Program, which makes our electrochemical corrosion laboratory, corrosion consulting and anti-corrosion technology conveniently available for your R&D program. Contact: rustdr@pairodocspro.com; 608-831-2076; www.pairodocspro.com. Back articles of Corrosion Corner are available from Spray. Thanks for your interest and I’ll see you in February. Spray January 2017 Spray 25
Spray January 2017
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