Materials Performance Supplements


Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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Removable Coatings for Up to One Year Service Life in the Oil and Gas Market Markus Bie B er, Cortec Corp., St. Paul, Minnesota, USA The oil and gas industry has a tremen- dous need for the protection of assets during shipment and storage. Newer advances have allowed the use of the vapor phase corrosion inhibitor (VCI) technology to be incorporated into temporary coatings that are designed to provide corrosion protection in ex- treme environments, yet still be easily removable compared to the older tra- ditional wax-type coatings made from hydrocarbons. By incorporating the VCI technology into these temporary coatings, it allows the use of thinner film thicknesses and less reliance on a thick barrier to keep contaminants away from the surface. Vapor phase corrosion inhibitors (VCIs) a re a c or ro si on i nhi bitor t e ch n o l o g y that is comprised of very small particles that are attracted to a metal substrate. They come in various formulations that are dependent on the type of system they will be used in; for example, films, oils, coatings, cleaners, etc. There are also a variety of for- mulations that provide protection in ferrous, nonferrous, or multi-metal applications. Other variables include the amount of vapor phase compared to contact phase inhibitors. How VCIs Work in a Coating VCIs are formulated into a coating through a complex development process that involves determining chemical com- patibility of the VCIs with the other com- ponents of the coating, such as the resin, solvents, pigments, and other additives used for a variety of reasons. VCIs work by adsorb- ing onto the metal surface in a nonreactive attractive capacity ; in other words, they are attracted to the metal through the particle charge. 1 How VCIs Compare to Traditional Inhibitors Traditional inhibitor systems use inor- ganic metal particles such as zincs, chro- mates, aluminum, and others. Additionally, traditional inhibitor systems often rely on thick barriers to prevent moisture and oxy- gen from getting to the substrate. VCIs com- pare with traditional inhibitor systems by using smaller particles as well as relying not only on contact inhibition but also vapor phase inhibition, providing more complete coverage and protection of the surface. 2-3 This is illustrated in Figures 1 and 2. Types of Coating Systems That Can Use VCIs VCIs can be used with most coating systems. There are many variations of VCIs and the key is to choose the correct VCI for the corresponding coating system by checking compatibility, effectiveness, and processability. Compatibility is determined using bench ladder tests that use various concentrations of VCIs and various ver- sions of VCIs to determine if there is phase separation, gelling, or particle generation. Typically this is done visually and the for- mulating chemist will determine if the results are acceptable. PROTECTIVE COATINGS FIGURE 1 VCIs provide more complete coverage and protection of a surface than traditional inhibitor systems. 4 FIGURE 2 The larger platelets are representative of traditional inhibitors that are unable to fill the micro-crevices, leaving gaps where corrosion can start and/or grow. 5 16 JUNE 2018 MATERIALS PERFORMANCE CORTEC SUPPLEMENT TO MP

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