Corrosion Rate Calculator

Corrosion rate in mils or millimeters per year is fundamentally a measure of how much material THICKNESS is being lost, not just how much mass. A given weight loss corresponds to a smaller volume (and therefore a thinner layer removed) in a denser material than in a lighter one, so density appears in the denominator of the ASTM G1 formula to convert mass loss into a penetration-rate figure.

A mil is one-thousandth of an inch, and MPY expresses corrosion rate as how many mils of material thickness would be lost per year if the measured rate continued steadily. It's the traditional unit in North American corrosion engineering, useful for comparing against a component's wall thickness or corrosion allowance to estimate remaining service life.

A 6mm wall is used here purely as an illustrative reference point for a typical pipe or vessel wall, not a measurement of your actual equipment. To estimate the real remaining life of a specific component, divide its actual wall thickness (minus any required corrosion allowance) by the calculated corrosion rate in mm/year instead of relying on this generic reference figure.

Not necessarily -- the weight-loss method reports a single average rate across the entire exposed surface, but many real corrosion failures come from localized attack such as pitting, crevice corrosion, or stress corrosion cracking, which can perforate a wall far faster than the average rate implies while the rest of the surface looks fine. A low average MPY is a reassuring screening result, not proof that no localized damage is occurring.