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ASTM G78 MCA multiple crevice assembly crevice washer specimen for corrosion testing

ASTM G78 MCA Test Specimens

Metaspec provides multiple crevice assemblies (MCA), including test panels, specimens, coupons, crevice washers, and fasteners used in ASTM G78 (Crevice Corrosion Testing of Iron-Base and Nickel-Base Stainless Alloys in Seawater and Other Chloride-Containing Aqueous Environments).


Multiple crevice assemblies consist of nonmetallic segmented washers (commonly called crevice washers), which have grooves and plateaus on one side, and separate metal or non-metallic specimens. Crevice washers can be made in different sizes and forms; an example is shown in ASTM G78 Figure 3. For metal-to-metal crevice-corrosion tests, two crevice washers are fastened to a larger specimen or panel. The fasteners, often a nut and bolt, may be metallic or nonmetallic. When the crevice washer is fastened to a metal panel, the grooves and plateaus in the crevice washer create exposed and protected areas on the test panel. After the test, the corrosion on the specimen is examined and evaluated.


ASTM G78 describes a variety of metal and non-metallic test specimens, which can be made from a range of different materials, alloys, and in different sizes or configurations. Because these different variables can create different corrosion conditions, ASTM G78 suggests using three of each specimen type during testing. If necessary, more specimens can be used to establish reproducibility. 


Please contact Metaspec with information about your project to request a quote. Please specify the specimen material, size, configuration and quantity of each type. 

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