KEVOS® MAKEOS · Materials
Corrosion Rate from Mass Loss
How fast is this metal corroding, and how long will the corrosion allowance last?
Uniform corrosion rate from a coupon’s mass loss, area, exposure time and density (ASTM G1 method), in mm/year and mils/year, with the remaining life of a corrosion allowance.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Mass loss | mg | Mass loss after cleaning, from before and after weighing. |
| Exposed area | cm² | Total exposed surface area of the coupon. |
| Exposure time | h | Exposure time. |
| Metal density | g/cm³ | Density of the metal (carbon steel 7.86, stainless about 7.9, copper 8.96 g/cm³). |
| Remaining corrosion allowance | mm | Wall thickness still available before the minimum required thickness. |
Method and formulas
- CR (mm/y) = 87.6 × W ÷ (ρ A T), W in mg, A in cm², T in hours.
- mils per year = mm/y × 39.37.
- Remaining life = allowance ÷ rate.
- Example: 120 mg lost from 20 cm² over 720 h is 0.092875 mm/y (3.6565 mpy).
Limitations
- Uniform corrosion only; pitting and crevice corrosion can perforate much sooner.
- Coupon conditions must represent the equipment (flow, temperature, deposits).
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Evaluate corrosion coupons from tanks, cooling water or process lines
- Estimate remaining life from a corrosion allowance
- Compare materials in a test
Who it is for
- Materials engineers
- Maintenance and reliability engineers
- Water treatment specialists
What you get
- Corrosion rate in mm/year and mils/year
- Remaining life of the allowance
Interpreting the result
- Back up coupon results with thickness measurements on the equipment.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1500–1516. Topic reference; no source tables or recommended settings are reproduced.
- ASTM G1 Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
