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Spray June 2017

W. Stephen tait, ph.D. Chief Science Officer & principal Consultant, pair O Docs professionals, LLC Corrosion Corner Aerosol container corrosion complexity Finally, in some instances, dip tube swelling could press the tube against the container body and bottom, forming a crevice between them. Dip tube crevice corrosion could also be general corrosion of the metal and coating, container body and/or bottom metal pitting corrosion and coating corrosion in the form of blistering or small delaminated patches. Figure 2 shows a thee-piece welded tinplated steel aerosol container with a cutaway. There are other types of steel aerosol containers that are tinplate but not welded, are not tinplate and not welded and have only one double seam either at the top or at the bottom of the container. I use the three-piece container for this discussion because its corrosion is slightly more complex than the others. Tinplated steel containers also have aerosol valve-curl crimps. In addition, steel top double seams are crevices in the vapor Hello, everyone. A spray package is actually a small pressure vessel, much like a carbonated beverage. However, metal spray packages are very strong and have internal pressures well below their maximum rated pressures. The internal pressure enables spray packages to effortlessly apply the amount of product consumers want and where they want it. Like most situations, corrosion is possible with all types of spray packages. Is spray package corrosion any different from corrosion of other structures, such as storage tanks, pipelines and chemical reactors? The types of materials used to fabricate spray packages in many ways makes their corrosion more complicated than corrosion of larger structures like a chemical reactor. I’ll use photographs of an aluminum aerosol container with a section cutout to show the inside, and a traditional welded three-piece tinplated steel aerosol container with a section cutout. Let’s start the discussion with the aluminum container in Figure 1, proceeding from container top to bottom. There is a small gap between the crimped valve and the container curl and this gap is a crevice. Consequently, crevice corrosion is possible as general corrosion of the metal and coating; valve and/or container top metal pitting corrosion and coating corrosion in the form of blistering or small delaminated patches. Valve and/or container top corrosion is also possible in the vapor area as general corrosion of the metal and coating; valve and/or container top metal pitting corrosion and coating corrosion in the form of blistering or small delaminated patches. The liquid-vapor interface and the liquid-propellant interface could also have general metal and coating corrosion, metal pitting corrosion and coating corrosion in the form of blistering or small delaminated patches. The liquid product area of the container could have general metal and coating corrosion, metal pitting corrosion and coating corrosion in the form of blistering or small delaminated patches. 28 Spray June 2017 Figure 1: Inside an aluminum aerosol container


Spray June 2017
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