MCI®-309 from Cortec Corporation is a vapor phase corrosion inhibitor powder. It provides corrosion protection of ferrous metals and aluminum in recessed areas, interior cavities, and voids. Suitable applications include segmental concrete bridges tendons; post tensioned box girder bridges; tubular structures, pipes, and vessels; equipment protection after hydrostatic testing; parts, components, and completed assemblies during shipping and storage; and prestressed tendons.
MCI-309 offers a dry method of protecting metals within an enclosed space. It vaporizes and adsorbs on the metal surfaces (carbon steel, stainless steel, aluminum), reaching all exposed areas, including recessed sections and interior cavities. This mixed inhibitor safeguards both the cathodic and anodic sites of metal. The monomolecular inhibiting layer that is created enables up to 24 months of continuous protection.
This MCI (migratory corrosion inhibitor) does not affect physical properties of concrete or grout (set time, strengths, etc.) and is safe for high tensile strength steel (will not cause hydrogen embrittlement). It also prevents further corrosion of pre-coated and painted surfaces.
MCI-309 requires little or no surface preparation—protected surfaces do not have to be cleaned prior to concrete or grout placement. The powder can be applied through dusting, fogging, or sprinkling. Fogging can be achieved with a low-pressure air hose and sandblast cup. Large, conventional sandblasting systems can also be used.
After application users cover, close, or seal the interior cavity or void. If the MCI-309 layer is disturbed by moisture or by opening the enclosed space, the layer is replenished by continuous vapor redeposition. The MCI layer does not need to be removed prior to processing or use and the powder can be removed by using a low-pressure air gun or water rinse.
MCI-309 does not contain silicates, phosphates, nitrites, or heavy metals and passed the VIA test per CC-027 (the method specifies testing 0.5 g of inhibitor of interest). The vapor phase corrosion inhibitor is available in five pound, 50 pound, and 100 pound lined drums. It should be stored in a sealed container in a dry warehouse avoiding direct exposure to sunlight, with temperature not exceeding 150°F. Shelf life is up to 24 months.
