millimeter per year

The millimetre per year is about 3.17 × 10⁻¹¹ metres per second, using this site's Julian year of exactly 365.25 days. It is the unit of geologically slow motion: tectonic plates separate at 20 to 150 mm/yr, sea level is rising at roughly 3.5 mm/yr, and general corrosion rates on steel are tabulated in it.

Watch out: Corrosion literature more often uses mils per year (mpy), thousandths of an inch, where 1 mpy is 0.0254 mm/yr. A rate quoted as "5" is a very different problem in the two units.

The millimetre per year is the international unit of corrosion rate, exactly 0.001 m/yr by decimal prefix. Its convenient property is that a rate in mm/yr multiplied by a design life in years gives the corrosion allowance directly in millimetres of wall thickness. General guidance in process work calls below 0.1 mm/yr excellent, 0.1 to 0.5 acceptable for most service, and above 1 mm/yr a material selection problem.

One millimeter per year in every speed unit

One millimeter per year in every corrosion rate unit

• Wind Chill (2001 North American Formula)
• Speed, Distance & Time
• Kinetic Energy
• Final Velocity (Uniform Acceleration)
• Displacement (Uniform Acceleration)
• Velocity-Displacement Relation (v² = v₀² + 2ad)

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