1. n. []
The weight loss of a corrosion coupon after exposure to a corrosive environment, expressed as mils (thousandths of an inch) per year penetration. Corrosion rate is calculated assuming uniform corrosion over the entire surface of the coupon. mpy = (weight loss in grams) * (22,300)/(Adt) mpy = corrosion rate (mils per year penetration) A = area of coupon (sq. in.) d = metal density of coupon (g/cm3) t = time of exposure in corrosive environment (days). It is important to note that the calculated values using this formula are not representative in cases of severe pitting. Therefore, a complete report, including a visual inspection, is required to determine either the type of attack or the appropriate corrosion control program. Corrosion rate is also known as corrosion ratio.
See related terms: corrosion coupon
