Patent ID: 8133383

Claim:
A method for measuring localized corrosion comprising: (a) placing a test electrode of a metal strip under investigation having length L in contact with a conductive fluid; (b) placing a temperature sensor in proximity to the metal strip; (c) measuring the resistance across the length L of the test electrode over a time period Δt to give first and second resistance values R 1 and R 2 ; (d) calculating changes in resistance due to temperature and subtracting them from measurements of R 1 and R 2 ; (e) determining polarization resistance R p from the relationship: R p = [ B a ⁢ B c ⁢ M ⁢ ⁢ W 2.3 ⁢ ( B a + B c ) · Density · 2 ⁢ F · L 2 ⁢ ρ ] ⁢ Δ ⁢ ⁢ t ⁡ ( R 1 ⁢ R 2 R 2 - R 1 ) ( Eq . ⁢ 1 ) where: B a and B c are Tafel slopes of anodic and cathodic reactions, respectively, obtained separately or from known values, MW is the molecular weight of the metal of the test electrode, Density being its density, ρ is the specific conductance of the metal, F is Faraday's constant, L 2 is the square of the length of the test electrode, and R 1 and R 2 are the resistance measurements over time period Δt; (f) measuring the potential of the metal strip, V, relative to a reference electrode; (g) performing these two measurements (c) and (f) independently; and (h) subsequently calculating the localized corrosion from I=V/Rp, wherein I is current, where the current is data are calculated from measurements by an electrical resistance (ER) technique.