Standard Guide for Crevice Corrosion Testing of Iron-Base and Nickel-Base Stainless Alloys in Seawater and Other Chloride-Containing Aqueous Environments
Crevice corrosion of iron-base and nickel-base stainless alloys can occur when an occlusion or crevice limits access of the bulk environment to a localized area of the metal surface. Localized environmental changes in this stagnant area can result in the formation of acidic/high chloride conditions that may result in initiation and propagation of crevice corrosion of susceptible alloys. In practice, crevices can generally be classified into two categories: (1) naturally occurring, that is, those created by biofouling, sediment, debris, deposits, etc., and (2) man-made, that is, those created during manufacturing, fabrication, assembly, or service. Crevice formers utilized in laboratory and field studies can represent actual geometric conditions encountered in some service applications. Use of such crevice formers in service-type environments are not considered accelerated test methods. The geometry of a crevice can be described by the dimensions of crevice gap and crevice depth. Crevice gap is identified as the width or space between the metal surface and the crevice former. Crevice depth is the distance from the mouth to the center or base of the crevice.
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