Corrosion Rate Calculations and Units

Corrosion Rate Calculations and Units

MPY (Mills Per Year)  continues as the most popular for Corrosion Rate in the world, despite metric units in recent years. MPY < 1 (outstanding) , MPY 1- 5 (Excellent), MPY 5-20 (Good), MPY 20 -50 (Fair), MPY 50 -200 (Poor), MPY 200+ ( Unacceptable ).


MPY = 534W/DAT

W = Weight loss (milligrams)
D  = Density (grams/cm3)
A  = Area (square inches)
T  = Time (Hours)


Another common unit of corrosion rate is mm/yr (knows as millimeters per year).
mm/yr < 0,02 (outstanding), mm/yr 0,02 – 0,1 (Excellent), mm/yr 0,1 – 0,5 (Good), mm/yr 0,5 – 1 (Fair), mm/yr 1-5 (Poor), mm/yr 5+ (Unacceptable).


mm/yr = 87,6 W / DAT

W = Weight loss (milligrams)
D  = Density (grams/cm3)
A  = Area (square inches)
T  = Time (Hours)

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